| blob | 423af772348fa4ccdfdb0ff1653b83373b105d62 |
1 /*
2 ** 2001 September 15
3 **
4 ** The author disclaims copyright to this source code. In place of
5 ** a legal notice, here is a blessing:
6 **
7 ** May you do good and not evil.
8 ** May you find forgiveness for yourself and forgive others.
9 ** May you share freely, never taking more than you give.
10 **
11 *************************************************************************
12 ** This file contains C code routines that are called by the parser
13 ** to handle INSERT statements in SQLite.
14 */
17 /*
18 ** Generate code that will
19 **
20 ** (1) acquire a lock for table pTab then
21 ** (2) open pTab as cursor iCur.
22 **
23 ** If pTab is a WITHOUT ROWID table, then it is the PRIMARY KEY index
24 ** for that table that is actually opened.
25 */
32 ){
50 }
51 }
53 /*
54 ** Return a pointer to the column affinity string associated with index
55 ** pIdx. A column affinity string has one character for each column in
56 ** the table, according to the affinity of the column:
57 **
58 ** Character Column affinity
59 ** ------------------------------
60 ** 'A' BLOB
61 ** 'B' TEXT
62 ** 'C' NUMERIC
63 ** 'D' INTEGER
64 ** 'F' REAL
65 **
66 ** An extra 'D' is appended to the end of the string to cover the
67 ** rowid that appears as the last column in every index.
68 **
69 ** Memory for the buffer containing the column index affinity string
70 ** is managed along with the rest of the Index structure. It will be
71 ** released when sqlite3DeleteIndex() is called.
72 */
74 /* The first time a column affinity string for a particular index is
75 ** required, it is allocated and populated here. It is then stored as
76 ** a member of the Index structure for subsequent use.
77 **
78 ** The column affinity string will eventually be deleted by
79 ** sqliteDeleteIndex() when the Index structure itself is cleaned
80 ** up.
81 */
88 }
101 }
105 }
108 }
112 }
115 /*
116 ** Compute an affinity string for a table. Space is obtained
117 ** from sqlite3DbMalloc(). The caller is responsible for freeing
118 ** the space when done.
119 */
128 }
129 }
133 }
135 }
137 /*
138 ** Make changes to the evolving bytecode to do affinity transformations
139 ** of values that are about to be gathered into a row for table pTab.
140 **
141 ** For ordinary (legacy, non-strict) tables:
142 ** -----------------------------------------
143 **
144 ** Compute the affinity string for table pTab, if it has not already been
145 ** computed. As an optimization, omit trailing SQLITE_AFF_BLOB affinities.
146 **
147 ** If the affinity string is empty (because it was all SQLITE_AFF_BLOB entries
148 ** which were then optimized out) then this routine becomes a no-op.
149 **
150 ** Otherwise if iReg>0 then code an OP_Affinity opcode that will set the
151 ** affinities for register iReg and following. Or if iReg==0,
152 ** then just set the P4 operand of the previous opcode (which should be
153 ** an OP_MakeRecord) to the affinity string.
154 **
155 ** A column affinity string has one character per column:
156 **
157 ** Character Column affinity
158 ** --------- ---------------
159 ** 'A' BLOB
160 ** 'B' TEXT
161 ** 'C' NUMERIC
162 ** 'D' INTEGER
163 ** 'E' REAL
164 **
165 ** For STRICT tables:
166 ** ------------------
167 **
168 ** Generate an appropropriate OP_TypeCheck opcode that will verify the
169 ** datatypes against the column definitions in pTab. If iReg==0, that
170 ** means an OP_MakeRecord opcode has already been generated and should be
171 ** the last opcode generated. The new OP_TypeCheck needs to be inserted
172 ** before the OP_MakeRecord. The new OP_TypeCheck should use the same
173 ** register set as the OP_MakeRecord. If iReg>0 then register iReg is
174 ** the first of a series of registers that will form the new record.
175 ** Apply the type checking to that array of registers.
176 */
182 /* Move the previous opcode (which should be OP_MakeRecord) forward
183 ** by one slot and insert a new OP_TypeCheck where the current
184 ** OP_MakeRecord is found */
193 /* Insert an isolated OP_Typecheck */
196 }
198 }
205 }
207 }
217 }
218 }
219 }
221 /*
222 ** Return non-zero if the table pTab in database iDb or any of its indices
223 ** have been opened at any point in the VDBE program. This is used to see if
224 ** a statement of the form "INSERT INTO <iDb, pTab> SELECT ..." can
225 ** run without using a temporary table for the results of the SELECT.
226 */
231 #ifndef SQLITE_OMIT_VIRTUALTABLE
233 #endif
243 }
247 }
248 }
249 }
250 #ifndef SQLITE_OMIT_VIRTUALTABLE
255 }
256 #endif
257 }
259 }
261 /* This walker callback will compute the union of colFlags flags for all
262 ** referenced columns in a CHECK constraint or generated column expression.
263 */
268 }
270 }
272 #ifndef SQLITE_OMIT_GENERATED_COLUMNS
273 /*
274 ** All regular columns for table pTab have been puts into registers
275 ** starting with iRegStore. The registers that correspond to STORED
276 ** or VIRTUAL columns have not yet been initialized. This routine goes
277 ** back and computes the values for those columns based on the previously
278 ** computed normal columns.
279 */
284 ){
286 Walker w;
295 /* Before computing generated columns, first go through and make sure
296 ** that appropriate affinity has been applied to the regular columns
297 */
302 /* Change the OP_Affinity argument to '@' (NONE) for all stored
303 ** columns. '@' is the no-op affinity and those columns have not
304 ** yet been computed. */
312 }
315 }
316 jj++;
317 }
319 /* If an OP_TypeCheck was generated because the table is STRICT,
320 ** then set the P3 operand to indicate that generated columns should
321 ** not be checked */
323 }
324 }
326 /* Because there can be multiple generated columns that refer to one another,
327 ** this is a two-pass algorithm. On the first pass, mark all generated
328 ** columns as "not available".
329 */
335 }
336 }
343 /* On the second pass, compute the value of each NOT-AVAILABLE column.
344 ** Companion code in the TK_COLUMN case of sqlite3ExprCodeTarget() will
345 ** compute dependencies and mark remove the COLSPAN_NOTAVAIL mark, as
346 ** they are needed.
347 */
363 }
369 }
370 }
374 }
376 }
380 #ifndef SQLITE_OMIT_AUTOINCREMENT
381 /*
382 ** Locate or create an AutoincInfo structure associated with table pTab
383 ** which is in database iDb. Return the register number for the register
384 ** that holds the maximum rowid. Return zero if pTab is not an AUTOINCREMENT
385 ** table. (Also return zero when doing a VACUUM since we do not want to
386 ** update the AUTOINCREMENT counters during a VACUUM.)
387 **
388 ** There is at most one AutoincInfo structure per table even if the
389 ** same table is autoincremented multiple times due to inserts within
390 ** triggers. A new AutoincInfo structure is created if this is the
391 ** first use of table pTab. On 2nd and subsequent uses, the original
392 ** AutoincInfo structure is used.
393 **
394 ** Four consecutive registers are allocated:
395 **
396 ** (1) The name of the pTab table.
397 ** (2) The maximum ROWID of pTab.
398 ** (3) The rowid in sqlite_sequence of pTab
399 ** (4) The original value of the max ROWID in pTab, or NULL if none
400 **
401 ** The 2nd register is the one that is returned. That is all the
402 ** insert routine needs to know about.
403 */
408 ){
413 ){
418 /* Verify that the sqlite_sequence table exists and is an ordinary
419 ** rowid table with exactly two columns.
420 ** Ticket d8dc2b3a58cd5dc2918a1d4acb 2018-05-23 */
425 ){
429 }
445 }
447 }
449 }
451 /*
452 ** This routine generates code that will initialize all of the
453 ** register used by the autoincrement tracker.
454 */
462 /* This routine is never called during trigger-generation. It is
463 ** only called from the top-level */
483 };
505 }
506 }
508 /*
509 ** Update the maximum rowid for an autoincrement calculation.
510 **
511 ** This routine should be called when the regRowid register holds a
512 ** new rowid that is about to be inserted. If that new rowid is
513 ** larger than the maximum rowid in the memId memory cell, then the
514 ** memory cell is updated.
515 */
519 }
520 }
522 /*
523 ** This routine generates the code needed to write autoincrement
524 ** maximum rowid values back into the sqlite_sequence register.
525 ** Every statement that might do an INSERT into an autoincrement
526 ** table (either directly or through triggers) needs to call this
527 ** routine just before the "exit" code.
528 */
543 };
564 }
565 }
568 }
569 #else
570 /*
571 ** If SQLITE_OMIT_AUTOINCREMENT is defined, then the three routines
572 ** above are all no-ops
573 */
574 # define autoIncBegin(A,B,C) (0)
575 # define autoIncStep(A,B,C)
579 /* Forward declaration */
586 );
588 /*
589 ** This routine is called to handle SQL of the following forms:
590 **
591 ** insert into TABLE (IDLIST) values(EXPRLIST),(EXPRLIST),...
592 ** insert into TABLE (IDLIST) select
593 ** insert into TABLE (IDLIST) default values
594 **
595 ** The IDLIST following the table name is always optional. If omitted,
596 ** then a list of all (non-hidden) columns for the table is substituted.
597 ** The IDLIST appears in the pColumn parameter. pColumn is NULL if IDLIST
598 ** is omitted.
599 **
600 ** For the pSelect parameter holds the values to be inserted for the
601 ** first two forms shown above. A VALUES clause is really just short-hand
602 ** for a SELECT statement that omits the FROM clause and everything else
603 ** that follows. If the pSelect parameter is NULL, that means that the
604 ** DEFAULT VALUES form of the INSERT statement is intended.
605 **
606 ** The code generated follows one of four templates. For a simple
607 ** insert with data coming from a single-row VALUES clause, the code executes
608 ** once straight down through. Pseudo-code follows (we call this
609 ** the "1st template"):
610 **
611 ** open write cursor to <table> and its indices
612 ** put VALUES clause expressions into registers
613 ** write the resulting record into <table>
614 ** cleanup
615 **
616 ** The three remaining templates assume the statement is of the form
617 **
618 ** INSERT INTO <table> SELECT ...
619 **
620 ** If the SELECT clause is of the restricted form "SELECT * FROM <table2>" -
621 ** in other words if the SELECT pulls all columns from a single table
622 ** and there is no WHERE or LIMIT or GROUP BY or ORDER BY clauses, and
623 ** if <table2> and <table1> are distinct tables but have identical
624 ** schemas, including all the same indices, then a special optimization
625 ** is invoked that copies raw records from <table2> over to <table1>.
626 ** See the xferOptimization() function for the implementation of this
627 ** template. This is the 2nd template.
628 **
629 ** open a write cursor to <table>
630 ** open read cursor on <table2>
631 ** transfer all records in <table2> over to <table>
632 ** close cursors
633 ** foreach index on <table>
634 ** open a write cursor on the <table> index
635 ** open a read cursor on the corresponding <table2> index
636 ** transfer all records from the read to the write cursors
637 ** close cursors
638 ** end foreach
639 **
640 ** The 3rd template is for when the second template does not apply
641 ** and the SELECT clause does not read from <table> at any time.
642 ** The generated code follows this template:
643 **
644 ** X <- A
645 ** goto B
646 ** A: setup for the SELECT
647 ** loop over the rows in the SELECT
648 ** load values into registers R..R+n
649 ** yield X
650 ** end loop
651 ** cleanup after the SELECT
652 ** end-coroutine X
653 ** B: open write cursor to <table> and its indices
654 ** C: yield X, at EOF goto D
655 ** insert the select result into <table> from R..R+n
656 ** goto C
657 ** D: cleanup
658 **
659 ** The 4th template is used if the insert statement takes its
660 ** values from a SELECT but the data is being inserted into a table
661 ** that is also read as part of the SELECT. In the third form,
662 ** we have to use an intermediate table to store the results of
663 ** the select. The template is like this:
664 **
665 ** X <- A
666 ** goto B
667 ** A: setup for the SELECT
668 ** loop over the tables in the SELECT
669 ** load value into register R..R+n
670 ** yield X
671 ** end loop
672 ** cleanup after the SELECT
673 ** end co-routine R
674 ** B: open temp table
675 ** L: yield X, at EOF goto M
676 ** insert row from R..R+n into temp table
677 ** goto L
678 ** M: open write cursor to <table> and its indices
679 ** rewind temp table
680 ** C: loop over rows of intermediate table
681 ** transfer values form intermediate table into <table>
682 ** end loop
683 ** D: cleanup
684 */
692 ){
716 /* Register allocations */
725 #ifndef SQLITE_OMIT_TRIGGER
729 #endif
735 }
739 /* If the Select object is really just a simple VALUES() list with a
740 ** single row (the common case) then keep that one row of values
741 ** and discard the other (unused) parts of the pSelect object
742 */
748 }
750 /* Locate the table into which we will be inserting new information.
751 */
756 }
762 }
765 /* Figure out if we have any triggers and if the table being
766 ** inserted into is a view
767 */
768 #ifndef SQLITE_OMIT_TRIGGER
771 #else
772 # define pTrigger 0
773 # define tmask 0
774 # define isView 0
775 #endif
776 #ifdef SQLITE_OMIT_VIEW
777 # undef isView
778 # define isView 0
779 #endif
782 #if TREETRACE_ENABLED
787 }
788 #endif
790 /* If pTab is really a view, make sure it has been initialized.
791 ** ViewGetColumnNames() is a no-op if pTab is not a view.
792 */
795 }
797 /* Cannot insert into a read-only table.
798 */
801 }
803 /* Allocate a VDBE
804 */
810 #ifndef SQLITE_OMIT_XFER_OPT
811 /* If the statement is of the form
812 **
813 ** INSERT INTO <table1> SELECT * FROM <table2>;
814 **
815 ** Then special optimizations can be applied that make the transfer
816 ** very fast and which reduce fragmentation of indices.
817 **
818 ** This is the 2nd template.
819 */
824 ){
828 }
831 /* If this is an AUTOINCREMENT table, look up the sequence number in the
832 ** sqlite_sequence table and store it in memory cell regAutoinc.
833 */
836 /* Allocate a block registers to hold the rowid and the values
837 ** for all columns of the new row.
838 */
842 regRowid++;
844 }
847 /* If the INSERT statement included an IDLIST term, then make sure
848 ** all elements of the IDLIST really are columns of the table and
849 ** remember the column indices.
850 **
851 ** If the table has an INTEGER PRIMARY KEY column and that column
852 ** is named in the IDLIST, then record in the ipkColumn variable
853 ** the index into IDLIST of the primary key column. ipkColumn is
854 ** the index of the primary key as it appears in IDLIST, not as
855 ** is appears in the original table. (The index of the INTEGER
856 ** PRIMARY KEY in the original table is pTab->iPKey.) After this
857 ** loop, if ipkColumn==(-1), that means that integer primary key
858 ** is unspecified, and hence the table is either WITHOUT ROWID or
859 ** it will automatically generated an integer primary key.
860 **
861 ** bIdListInOrder is true if the columns in IDLIST are in storage
862 ** order. This enables an optimization that avoids shuffling the
863 ** columns into storage order. False negatives are harmless,
864 ** but false positives will cause database corruption.
865 */
872 }
880 }
881 #ifndef SQLITE_OMIT_GENERATED_COLUMNS
887 }
888 #endif
890 }
891 }
901 }
902 }
903 }
904 }
906 /* Figure out how many columns of data are supplied. If the data
907 ** is coming from a SELECT statement, then generate a co-routine that
908 ** produces a single row of the SELECT on each invocation. The
909 ** co-routine is the common header to the 3rd and 4th templates.
910 */
912 /* Data is coming from a SELECT or from a multi-row VALUES clause.
913 ** Generate a co-routine to run the SELECT. */
934 /* Set useTempTable to TRUE if the result of the SELECT statement
935 ** should be written into a temporary table (template 4). Set to
936 ** FALSE if each output row of the SELECT can be written directly into
937 ** the destination table (template 3).
938 **
939 ** A temp table must be used if the table being updated is also one
940 ** of the tables being read by the SELECT statement. Also use a
941 ** temp table in the case of row triggers.
942 */
945 }
948 /* Invoke the coroutine to extract information from the SELECT
949 ** and add it to a transient table srcTab. The code generated
950 ** here is from the 4th template:
951 **
952 ** B: open temp table
953 ** L: yield X, goto M at EOF
954 ** insert row from R..R+n into temp table
955 ** goto L
956 ** M: ...
957 */
974 }
976 /* This is the case if the data for the INSERT is coming from a
977 ** single-row VALUES clause
978 */
979 NameContext sNC;
988 }
991 }
992 }
994 /* If there is no IDLIST term but the table has an integer primary
995 ** key, the set the ipkColumn variable to the integer primary key
996 ** column index in the original table definition.
997 */
1000 #ifndef SQLITE_OMIT_GENERATED_COLUMNS
1008 ipkColumn--;
1009 }
1010 }
1011 }
1012 #endif
1014 /* Make sure the number of columns in the source data matches the number
1015 ** of columns to be inserted into the table.
1016 */
1023 }
1024 }
1030 }
1031 }
1035 }
1037 /* Initialize the count of rows to be inserted
1038 */
1043 ){
1046 }
1048 /* If this is not a view, open the table and and all indices */
1056 }
1061 }
1063 }
1064 #ifndef SQLITE_OMIT_UPSERT
1071 }
1075 }
1078 }
1089 }
1090 }
1093 }
1094 #endif
1097 /* This is the top of the main insertion loop */
1099 /* This block codes the top of loop only. The complete loop is the
1100 ** following pseudocode (template 4):
1101 **
1102 ** rewind temp table, if empty goto D
1103 ** C: loop over rows of intermediate table
1104 ** transfer values form intermediate table into <table>
1105 ** end loop
1106 ** D: ...
1107 */
1111 /* This block codes the top of loop only. The complete loop is the
1112 ** following pseudocode (template 3):
1113 **
1114 ** C: yield X, at EOF goto D
1115 ** insert the select result into <table> from R..R+n
1116 ** goto C
1117 ** D: ...
1118 */
1123 /* tag-20191021-001: If the INTEGER PRIMARY KEY is being generated by the
1124 ** SELECT, go ahead and copy the value into the rowid slot now, so that
1125 ** the value does not get overwritten by a NULL at tag-20191021-002. */
1127 }
1128 }
1130 /* Compute data for ordinary columns of the new entry. Values
1131 ** are written in storage order into registers starting with regData.
1132 ** Only ordinary columns are computed in this loop. The rowid
1133 ** (if there is one) is computed later and generated columns are
1134 ** computed after the rowid since they might depend on the value
1135 ** of the rowid.
1136 */
1141 u32 colFlags;
1144 /* tag-20191021-002: References to the INTEGER PRIMARY KEY are filled
1145 ** using the rowid. So put a NULL in the IPK slot of the record to avoid
1146 ** using excess space. The file format definition requires this extra
1147 ** NULL - we cannot optimize further by skipping the column completely */
1150 }
1152 nHidden++;
1154 /* Virtual columns do not participate in OP_MakeRecord. So back up
1155 ** iRegStore by one slot to compensate for the iRegStore++ in the
1156 ** outer for() loop */
1157 iRegStore--;
1160 /* Stored columns are computed later. But if there are BEFORE
1161 ** triggers, the slots used for stored columns will be OP_Copy-ed
1162 ** to a second block of registers, so the register needs to be
1163 ** initialized to NULL to avoid an uninitialized register read */
1166 }
1169 /* Hidden columns that are not explicitly named in the INSERT
1170 ** get there default value */
1173 iRegStore);
1175 }
1176 }
1181 /* A column not named in the insert column list gets its
1182 ** default value */
1185 iRegStore);
1187 }
1190 /* This is INSERT INTO ... DEFAULT VALUES. Load the default value. */
1193 iRegStore);
1197 }
1204 }
1211 }
1212 }
1213 }
1216 /* Run the BEFORE and INSTEAD OF triggers, if there are any
1217 */
1222 /* build the NEW.* reference row. Note that if there is an INTEGER
1223 ** PRIMARY KEY into which a NULL is being inserted, that NULL will be
1224 ** translated into a unique ID for the row. But on a BEFORE trigger,
1225 ** we do not know what the unique ID will be (because the insert has
1226 ** not happened yet) so we substitute a rowid of -1
1227 */
1238 }
1243 }
1245 /* Copy the new data already generated. */
1249 #ifndef SQLITE_OMIT_GENERATED_COLUMNS
1250 /* Compute the new value for generated columns after all other
1251 ** columns have already been computed. This must be done after
1252 ** computing the ROWID in case one of the generated columns
1253 ** refers to the ROWID. */
1258 }
1259 #endif
1261 /* If this is an INSERT on a view with an INSTEAD OF INSERT trigger,
1262 ** do not attempt any conversions before assembling the record.
1263 ** If this is a real table, attempt conversions as required by the
1264 ** table column affinities.
1265 */
1268 }
1270 /* Fire BEFORE or INSTEAD OF triggers */
1275 }
1279 /* The row that the VUpdate opcode will delete: none */
1281 }
1283 /* Compute the new rowid */
1287 /* Rowid already initialized at tag-20191021-001 */
1295 }
1296 }
1297 /* If the PRIMARY KEY expression is NULL, then use OP_NewRowid
1298 ** to generate a unique primary key value.
1299 */
1309 }
1311 }
1317 }
1320 #ifndef SQLITE_OMIT_GENERATED_COLUMNS
1321 /* Compute the new value for generated columns after all other
1322 ** columns have already been computed. This must be done after
1323 ** computing the ROWID in case one of the generated columns
1324 ** is derived from the INTEGER PRIMARY KEY. */
1327 }
1328 #endif
1330 /* Generate code to check constraints and generate index keys and
1331 ** do the insertion.
1332 */
1333 #ifndef SQLITE_OMIT_VIRTUALTABLE
1341 #endif
1342 {
1347 );
1350 }
1352 /* Set the OPFLAG_USESEEKRESULT flag if either (a) there are no REPLACE
1353 ** constraints or (b) there are no triggers and this table is not a
1354 ** parent table in a foreign key constraint. It is safe to set the
1355 ** flag in the second case as if any REPLACE constraint is hit, an
1356 ** OP_Delete or OP_IdxDelete instruction will be executed on each
1357 ** cursor that is disturbed. And these instructions both clear the
1358 ** VdbeCursor.seekResult variable, disabling the OPFLAG_USESEEKRESULT
1359 ** functionality. */
1363 );
1364 }
1365 #ifdef SQLITE_ALLOW_ROWID_IN_VIEW
1367 /* If there is a RETURNING clause, populate the rowid register with
1368 ** constant value -1, in case one or more of the returned expressions
1369 ** refer to the "rowid" of the view. */
1371 #endif
1372 }
1374 /* Update the count of rows that are inserted
1375 */
1378 }
1381 /* Code AFTER triggers */
1384 }
1386 /* The bottom of the main insertion loop, if the data source
1387 ** is a SELECT statement.
1388 */
1396 #ifdef SQLITE_DEBUG
1397 /* If we are jumping back to an OP_Yield that is preceded by an
1398 ** OP_ReleaseReg, set the p5 flag on the OP_Goto so that the
1399 ** OP_ReleaseReg will be included in the loop. */
1403 }
1404 #endif
1406 }
1408 #ifndef SQLITE_OMIT_XFER_OPT
1409 insert_end:
1411 /* Update the sqlite_sequence table by storing the content of the
1412 ** maximum rowid counter values recorded while inserting into
1413 ** autoincrement tables.
1414 */
1417 }
1419 /*
1420 ** Return the number of rows inserted. If this routine is
1421 ** generating code because of a call to sqlite3NestedParse(), do not
1422 ** invoke the callback function.
1423 */
1426 }
1428 insert_cleanup:
1435 }
1437 /* Make sure "isView" and other macros defined above are undefined. Otherwise
1438 ** they may interfere with compilation of other functions in this file
1439 ** (or in another file, if this file becomes part of the amalgamation). */
1440 #ifdef isView
1441 #undef isView
1442 #endif
1443 #ifdef pTrigger
1444 #undef pTrigger
1445 #endif
1446 #ifdef tmask
1447 #undef tmask
1448 #endif
1450 /*
1451 ** Meanings of bits in of pWalker->eCode for
1452 ** sqlite3ExprReferencesUpdatedColumn()
1453 */
1457 /* This is the Walker callback from sqlite3ExprReferencesUpdatedColumn().
1458 * Set bit 0x01 of pWalker->eCode if pWalker->eCode to 0 and if this
1459 ** expression node references any of the
1460 ** columns that are being modifed by an UPDATE statement.
1461 */
1468 }
1471 }
1472 }
1474 }
1476 /*
1477 ** pExpr is a CHECK constraint on a row that is being UPDATE-ed. The
1478 ** only columns that are modified by the UPDATE are those for which
1479 ** aiChng[i]>=0, and also the ROWID is modified if chngRowid is true.
1480 **
1481 ** Return true if CHECK constraint pExpr uses any of the
1482 ** changing columns (or the rowid if it is changing). In other words,
1483 ** return true if this CHECK constraint must be validated for
1484 ** the new row in the UPDATE statement.
1485 **
1486 ** 2018-09-15: pExpr might also be an expression for an index-on-expressions.
1487 ** The operation of this routine is the same - return true if an only if
1488 ** the expression uses one or more of columns identified by the second and
1489 ** third arguments.
1490 */
1495 ){
1496 Walker w;
1505 }
1511 }
1513 /*
1514 ** The sqlite3GenerateConstraintChecks() routine usually wants to visit
1515 ** the indexes of a table in the order provided in the Table->pIndex list.
1516 ** However, sometimes (rarely - when there is an upsert) it wants to visit
1517 ** the indexes in a different order. The following data structures accomplish
1518 ** this.
1519 **
1520 ** The IndexIterator object is used to walk through all of the indexes
1521 ** of a table in either Index.pNext order, or in some other order established
1522 ** by an array of IndexListTerm objects.
1523 */
1538 };
1540 /* When IndexIterator.eType==1, then each index is an array of instances
1541 ** of the following object
1542 */
1546 };
1548 /* Return the first index on the list */
1557 }
1558 }
1560 /* Return the next index from the list. Return NULL when out of indexes */
1567 }
1574 }
1575 }
1577 /*
1578 ** Generate code to do constraint checks prior to an INSERT or an UPDATE
1579 ** on table pTab.
1580 **
1581 ** The regNewData parameter is the first register in a range that contains
1582 ** the data to be inserted or the data after the update. There will be
1583 ** pTab->nCol+1 registers in this range. The first register (the one
1584 ** that regNewData points to) will contain the new rowid, or NULL in the
1585 ** case of a WITHOUT ROWID table. The second register in the range will
1586 ** contain the content of the first table column. The third register will
1587 ** contain the content of the second table column. And so forth.
1588 **
1589 ** The regOldData parameter is similar to regNewData except that it contains
1590 ** the data prior to an UPDATE rather than afterwards. regOldData is zero
1591 ** for an INSERT. This routine can distinguish between UPDATE and INSERT by
1592 ** checking regOldData for zero.
1593 **
1594 ** For an UPDATE, the pkChng boolean is true if the true primary key (the
1595 ** rowid for a normal table or the PRIMARY KEY for a WITHOUT ROWID table)
1596 ** might be modified by the UPDATE. If pkChng is false, then the key of
1597 ** the iDataCur content table is guaranteed to be unchanged by the UPDATE.
1598 **
1599 ** For an INSERT, the pkChng boolean indicates whether or not the rowid
1600 ** was explicitly specified as part of the INSERT statement. If pkChng
1601 ** is zero, it means that the either rowid is computed automatically or
1602 ** that the table is a WITHOUT ROWID table and has no rowid. On an INSERT,
1603 ** pkChng will only be true if the INSERT statement provides an integer
1604 ** value for either the rowid column or its INTEGER PRIMARY KEY alias.
1605 **
1606 ** The code generated by this routine will store new index entries into
1607 ** registers identified by aRegIdx[]. No index entry is created for
1608 ** indices where aRegIdx[i]==0. The order of indices in aRegIdx[] is
1609 ** the same as the order of indices on the linked list of indices
1610 ** at pTab->pIndex.
1611 **
1612 ** (2019-05-07) The generated code also creates a new record for the
1613 ** main table, if pTab is a rowid table, and stores that record in the
1614 ** register identified by aRegIdx[nIdx] - in other words in the first
1615 ** entry of aRegIdx[] past the last index. It is important that the
1616 ** record be generated during constraint checks to avoid affinity changes
1617 ** to the register content that occur after constraint checks but before
1618 ** the new record is inserted.
1619 **
1620 ** The caller must have already opened writeable cursors on the main
1621 ** table and all applicable indices (that is to say, all indices for which
1622 ** aRegIdx[] is not zero). iDataCur is the cursor for the main table when
1623 ** inserting or updating a rowid table, or the cursor for the PRIMARY KEY
1624 ** index when operating on a WITHOUT ROWID table. iIdxCur is the cursor
1625 ** for the first index in the pTab->pIndex list. Cursors for other indices
1626 ** are at iIdxCur+N for the N-th element of the pTab->pIndex list.
1627 **
1628 ** This routine also generates code to check constraints. NOT NULL,
1629 ** CHECK, and UNIQUE constraints are all checked. If a constraint fails,
1630 ** then the appropriate action is performed. There are five possible
1631 ** actions: ROLLBACK, ABORT, FAIL, REPLACE, and IGNORE.
1632 **
1633 ** Constraint type Action What Happens
1634 ** --------------- ---------- ----------------------------------------
1635 ** any ROLLBACK The current transaction is rolled back and
1636 ** sqlite3_step() returns immediately with a
1637 ** return code of SQLITE_CONSTRAINT.
1638 **
1639 ** any ABORT Back out changes from the current command
1640 ** only (do not do a complete rollback) then
1641 ** cause sqlite3_step() to return immediately
1642 ** with SQLITE_CONSTRAINT.
1643 **
1644 ** any FAIL Sqlite3_step() returns immediately with a
1645 ** return code of SQLITE_CONSTRAINT. The
1646 ** transaction is not rolled back and any
1647 ** changes to prior rows are retained.
1648 **
1649 ** any IGNORE The attempt in insert or update the current
1650 ** row is skipped, without throwing an error.
1651 ** Processing continues with the next row.
1652 ** (There is an immediate jump to ignoreDest.)
1653 **
1654 ** NOT NULL REPLACE The NULL value is replace by the default
1655 ** value for that column. If the default value
1656 ** is NULL, the action is the same as ABORT.
1657 **
1658 ** UNIQUE REPLACE The other row that conflicts with the row
1659 ** being inserted is removed.
1660 **
1661 ** CHECK REPLACE Illegal. The results in an exception.
1662 **
1663 ** Which action to take is determined by the overrideError parameter.
1664 ** Or if overrideError==OE_Default, then the pParse->onError parameter
1665 ** is used. Or if pParse->onError==OE_Default then the onError value
1666 ** for the constraint is used.
1667 */
1682 ){
1700 /* Variables associated with retesting uniqueness constraints after
1701 ** replace triggers fire have run */
1716 /* pPk is the PRIMARY KEY index for WITHOUT ROWID tables and NULL for
1717 ** normal rowid tables. nPkField is the number of key fields in the
1718 ** pPk index or 1 for a rowid table. In other words, nPkField is the
1719 ** number of fields in the true primary key of the table. */
1726 }
1728 /* Record that this module has started */
1732 /* Test all NOT NULL constraints.
1733 */
1747 }
1750 nGenerated++;
1752 }
1754 /* Do not check NOT NULL on columns that do not change */
1756 }
1761 }
1765 ){
1772 }
1775 }
1785 nSeenReplace++;
1790 }
1793 /* no break */ deliberate_fall_through
1805 }
1811 }
1815 /* If there are no generated columns with NOT NULL constraints
1816 ** and no NOT NULL ON CONFLICT REPLACE constraints, then a single
1817 ** pass is sufficient */
1819 }
1822 #ifndef SQLITE_OMIT_GENERATED_COLUMNS
1824 /* If any NOT NULL ON CONFLICT REPLACE constraints fired on the
1825 ** first pass, recomputed values for all generated columns, as
1826 ** those values might depend on columns affected by the REPLACE.
1827 */
1829 }
1830 #endif
1834 /* Test all CHECK constraints
1835 */
1836 #ifndef SQLITE_OMIT_CHECK
1847 ){
1848 /* The check constraints do not reference any of the columns being
1849 ** updated so there is no point it verifying the check constraint */
1851 }
1855 }
1861 }
1871 P5_ConstraintCheck);
1872 }
1874 }
1876 }
1879 /* UNIQUE and PRIMARY KEY constraints should be handled in the following
1880 ** order:
1881 **
1882 ** (1) OE_Update
1883 ** (2) OE_Abort, OE_Fail, OE_Rollback, OE_Ignore
1884 ** (3) OE_Replace
1885 **
1886 ** OE_Fail and OE_Ignore must happen before any changes are made.
1887 ** OE_Update guarantees that only a single row will change, so it
1888 ** must happen before OE_Replace. Technically, OE_Abort and OE_Rollback
1889 ** could happen in any order, but they are grouped up front for
1890 ** convenience.
1891 **
1892 ** 2018-08-14: Ticket https://www.sqlite.org/src/info/908f001483982c43
1893 ** The order of constraints used to have OE_Update as (2) and OE_Abort
1894 ** and so forth as (1). But apparently PostgreSQL checks the OE_Update
1895 ** constraint before any others, so it had to be moved.
1896 **
1897 ** Constraint checking code is generated in this order:
1898 ** (A) The rowid constraint
1899 ** (B) Unique index constraints that do not have OE_Replace as their
1900 ** default conflict resolution strategy
1901 ** (C) Unique index that do use OE_Replace by default.
1902 **
1903 ** The ordering of (2) and (3) is accomplished by making sure the linked
1904 ** list of indexes attached to a table puts all OE_Replace indexes last
1905 ** in the list. See sqlite3CreateIndex() for where that happens.
1906 */
1913 /* There is just on ON CONFLICT clause and it has no constraint-target */
1916 /* A single ON CONFLICT DO NOTHING clause, without a constraint-target.
1917 ** Make all unique constraint resolution be OE_Ignore */
1921 /* A single ON CONFLICT DO UPDATE. Make all resolutions OE_Update */
1923 }
1925 /* Otherwise, we'll need to run the IndexListTerm array version of the
1926 ** iterator to ensure that all of the ON CONFLICT conditions are
1927 ** checked first and in order. */
1929 u64 nByte;
1934 }
1949 jj++;
1950 }
1955 i++;
1956 }
1961 i++;
1962 }
1964 }
1965 }
1967 /* Determine if it is possible that triggers (either explicitly coded
1968 ** triggers or FK resolution actions) might run as a result of deletes
1969 ** that happen when OE_Replace conflict resolution occurs. (Call these
1970 ** "replace triggers".) If any replace triggers run, we will need to
1971 ** recheck all of the uniqueness constraints after they have all run.
1972 ** But on the recheck, the resolution is OE_Abort instead of OE_Replace.
1973 **
1974 ** If replace triggers are a possibility, then
1975 **
1976 ** (1) Allocate register regTrigCnt and initialize it to zero.
1977 ** That register will count the number of replace triggers that
1978 ** fire. Constraint recheck only occurs if the number is positive.
1979 ** (2) Initialize pTrigger to the list of all DELETE triggers on pTab.
1980 ** (3) Initialize addrRecheck and lblRecheckOk
1981 **
1982 ** The uniqueness rechecking code will create a series of tests to run
1983 ** in a second pass. The addrRecheck and lblRecheckOk variables are
1984 ** used to link together these tests which are separated from each other
1985 ** in the generate bytecode.
1986 */
1988 /* There are not DELETE triggers nor FK constraints. No constraint
1989 ** rechecks are needed. */
1999 }
2001 /* Replace triggers might exist. Allocate the counter and
2002 ** initialize it to zero. */
2008 }
2009 }
2011 /* If rowid is changing, make sure the new rowid does not previously
2012 ** exist in the table.
2013 */
2017 /* Figure out what action to take in case of a rowid collision */
2023 }
2025 /* figure out whether or not upsert applies in this case */
2033 }
2034 }
2036 /* The first ON CONFLICT clause has a conflict target other than
2037 ** the IPK. We have to jump ahead to that first ON CONFLICT clause
2038 ** and then come back here and deal with the IPK afterwards */
2040 }
2041 }
2043 /* If the response to a rowid conflict is REPLACE but the response
2044 ** to some other UNIQUE constraint is FAIL or IGNORE, then we need
2045 ** to defer the running of the rowid conflict checking until after
2046 ** the UNIQUE constraints have run.
2047 */
2052 ){
2055 }
2058 /* pkChng!=0 does not mean that the rowid has changed, only that
2059 ** it might have changed. Skip the conflict logic below if the rowid
2060 ** is unchanged. */
2064 }
2066 /* Check to see if the new rowid already exists in the table. Skip
2067 ** the following conflict logic if it does not. */
2076 /* no break */ deliberate_fall_through
2077 }
2086 }
2088 /* If there are DELETE triggers on this table and the
2089 ** recursive-triggers flag is set, call GenerateRowDelete() to
2090 ** remove the conflicting row from the table. This will fire
2091 ** the triggers and remove both the table and index b-tree entries.
2092 **
2093 ** Otherwise, if there are no triggers or the recursive-triggers
2094 ** flag is not set, but the table has one or more indexes, call
2095 ** GenerateRowIndexDelete(). This removes the index b-tree entries
2096 ** only. The table b-tree entry will be replaced by the new entry
2097 ** when it is inserted.
2098 **
2099 ** If either GenerateRowDelete() or GenerateRowIndexDelete() is called,
2100 ** also invoke MultiWrite() to indicate that this VDBE may require
2101 ** statement rollback (if the statement is aborted after the delete
2102 ** takes place). Earlier versions called sqlite3MultiWrite() regardless,
2103 ** but being more selective here allows statements like:
2104 **
2105 ** REPLACE INTO t(rowid) VALUES($newrowid)
2106 **
2107 ** to run without a statement journal if there are no indexes on the
2108 ** table.
2109 */
2115 nReplaceTrig++;
2117 #ifdef SQLITE_ENABLE_PREUPDATE_HOOK
2119 /* This OP_Delete opcode fires the pre-update-hook only. It does
2120 ** not modify the b-tree. It is more efficient to let the coming
2121 ** OP_Insert replace the existing entry than it is to delete the
2122 ** existing entry and then insert a new one. */
2129 }
2130 }
2133 }
2134 #ifndef SQLITE_OMIT_UPSERT
2137 /* no break */ deliberate_fall_through
2138 }
2139 #endif
2144 }
2145 }
2152 }
2153 }
2155 /* Test all UNIQUE constraints by creating entries for each UNIQUE
2156 ** index and making sure that duplicate entries do not already exist.
2157 ** Compute the revised record entries for indices as we go.
2158 **
2159 ** This loop also handles the case of the PRIMARY KEY index for a
2160 ** WITHOUT ROWID table.
2161 */
2163 pIdx;
2165 ){
2177 }
2178 }
2183 }
2188 /* Skip partial indices for which the WHERE clause is not true */
2193 SQLITE_JUMPIFNULL);
2195 }
2197 /* Create a record for this index entry as it should appear after
2198 ** the insert or update. Store that record in the aRegIdx[ix] register
2199 */
2218 }
2219 }
2222 #ifdef SQLITE_ENABLE_NULL_TRIM
2225 }
2226 #endif
2229 /* In an UPDATE operation, if this index is the PRIMARY KEY index
2230 ** of a WITHOUT ROWID table and there has been no change the
2231 ** primary key, then no collision is possible. The collision detection
2232 ** logic below can all be skipped. */
2236 }
2238 /* Find out what action to take in case there is a uniqueness conflict */
2243 }
2248 }
2250 /* Figure out if the upsert clause applies to this index */
2256 }
2257 }
2259 /* Collision detection may be omitted if all of the following are true:
2260 ** (1) The conflict resolution algorithm is REPLACE
2261 ** (2) The table is a WITHOUT ROWID table
2262 ** (3) There are no secondary indexes on the table
2263 ** (4) No delete triggers need to be fired if there is a conflict
2264 ** (5) No FK constraint counters need to be updated if a conflict occurs.
2265 **
2266 ** This is not possible for ENABLE_PREUPDATE_HOOK builds, as the row
2267 ** must be explicitly deleted in order to ensure any pre-update hook
2268 ** is invoked. */
2270 #ifndef SQLITE_ENABLE_PREUPDATE_HOOK
2278 ){
2281 }
2284 /* Check to see if the new index entry will be unique */
2286 addrConflictCk =
2290 /* Generate code to handle collisions */
2295 /* Conflict only if the rowid of the existing index entry
2296 ** is different from old-rowid */
2301 }
2304 /* Extract the PRIMARY KEY from the end of the index entry and
2305 ** store it in registers regR..regR+nPk-1 */
2313 }
2314 }
2316 /* If currently processing the PRIMARY KEY of a WITHOUT ROWID
2317 ** table, only conflict if the new PRIMARY KEY values are actually
2318 ** different from the old. See TH3 withoutrowid04.test.
2319 **
2320 ** For a UNIQUE index, only conflict if the PRIMARY KEY values
2321 ** of the matched index row are different from the original PRIMARY
2322 ** KEY values of this row before the update. */
2334 }
2338 );
2342 }
2343 }
2344 }
2345 }
2347 /* Generate code that executes if the new index entry is not unique */
2359 }
2360 #ifndef SQLITE_OMIT_UPSERT
2363 /* no break */ deliberate_fall_through
2364 }
2365 #endif
2370 }
2381 nReplaceTrig++;
2382 }
2385 }
2391 }
2399 /* Here we insert code that will be invoked after all constraint
2400 ** checks have run, if and only if one or more replace triggers
2401 ** fired. */
2405 /* Bypass the recheck if this partial index is not defined
2406 ** for the current row */
2409 }
2410 /* Copy the constraint check code from above, except change
2411 ** the constraint-ok jump destination to be the address of
2412 ** the next retest block */
2415 /* The sqlite3VdbeAddOp4() call might reallocate the opcode array.
2416 ** Hence, make a complete copy of the opcode, rather than using
2417 ** a pointer to the opcode. */
2426 }
2431 }
2432 nConflictCk--;
2433 addrConflictCk++;
2434 }
2435 /* If the retest fails, issue an abort */
2439 }
2442 }
2443 }
2447 && upsertIpkReturn
2449 ){
2453 }
2454 }
2456 /* If the IPK constraint is a REPLACE, run it last */
2462 }
2464 /* Recheck all uniqueness constraints after replace triggers have run */
2474 }
2480 }
2482 }
2484 /* Generate the table record */
2491 }
2492 }
2496 }
2498 #ifdef SQLITE_ENABLE_NULL_TRIM
2499 /*
2500 ** Change the P5 operand on the last opcode (which should be an OP_MakeRecord)
2501 ** to be the number of columns in table pTab that must not be NULL-trimmed.
2502 **
2503 ** Or if no columns of pTab may be NULL-trimmed, leave P5 at zero.
2504 */
2506 u16 i;
2508 /* Records with omitted columns are only allowed for schema format
2509 ** version 2 and later (SQLite version 3.1.4, 2005-02-20). */
2515 }
2517 }
2518 #endif
2520 /*
2521 ** Table pTab is a WITHOUT ROWID table that is being written to. The cursor
2522 ** number is iCur, and register regData contains the new record for the
2523 ** PK index. This function adds code to invoke the pre-update hook,
2524 ** if one is registered.
2525 */
2526 #ifdef SQLITE_ENABLE_PREUPDATE_HOOK
2532 ){
2541 }
2542 #else
2543 # define codeWithoutRowidPreupdate(a,b,c,d)
2544 #endif
2546 /*
2547 ** This routine generates code to finish the INSERT or UPDATE operation
2548 ** that was started by a prior call to sqlite3GenerateConstraintChecks.
2549 ** A consecutive range of registers starting at regNewData contains the
2550 ** rowid and the content to be inserted.
2551 **
2552 ** The arguments to this routine should be the same as the first six
2553 ** arguments to sqlite3GenerateConstraintChecks.
2554 */
2565 ){
2574 );
2580 /* All REPLACE indexes are at the end of the list */
2588 }
2595 }
2596 }
2601 }
2608 }
2611 }
2614 }
2618 }
2620 }
2622 /*
2623 ** Allocate cursors for the pTab table and all its indices and generate
2624 ** code to open and initialized those cursors.
2625 **
2626 ** The cursor for the object that contains the complete data (normally
2627 ** the table itself, but the PRIMARY KEY index in the case of a WITHOUT
2628 ** ROWID table) is returned in *piDataCur. The first index cursor is
2629 ** returned in *piIdxCur. The number of indices is returned.
2630 **
2631 ** Use iBase as the first cursor (either the *piDataCur for rowid tables
2632 ** or the first index for WITHOUT ROWID tables) if it is non-negative.
2633 ** If iBase is negative, then allocate the next available cursor.
2634 **
2635 ** For a rowid table, *piDataCur will be exactly one less than *piIdxCur.
2636 ** For a WITHOUT ROWID table, *piDataCur will be somewhere in the range
2637 ** of *piIdxCurs, depending on where the PRIMARY KEY index appears on the
2638 ** pTab->pIndex list.
2639 **
2640 ** If pTab is a virtual table, then this routine is a no-op and the
2641 ** *piDataCur and *piIdxCur values are left uninitialized.
2642 */
2652 ){
2662 /* This routine is a no-op for virtual tables. Leave the output
2663 ** variables *piDataCur and *piIdxCur set to illegal cursor numbers
2664 ** for improved error detection. */
2667 }
2678 }
2686 }
2692 }
2693 }
2696 }
2699 #ifdef SQLITE_TEST
2700 /*
2701 ** The following global variable is incremented whenever the
2702 ** transfer optimization is used. This is used for testing
2703 ** purposes only - to make sure the transfer optimization really
2704 ** is happening when it is supposed to.
2705 */
2710 #ifndef SQLITE_OMIT_XFER_OPT
2711 /*
2712 ** Check to see if index pSrc is compatible as a source of data
2713 ** for index pDest in an insert transfer optimization. The rules
2714 ** for a compatible index:
2715 **
2716 ** * The index is over the same set of columns
2717 ** * The same DESC and ASC markings occurs on all columns
2718 ** * The same onError processing (OE_Abort, OE_Ignore, etc)
2719 ** * The same collating sequence on each column
2720 ** * The index has the exact same WHERE clause
2721 */
2728 }
2731 }
2735 }
2741 }
2742 }
2745 }
2748 }
2749 }
2752 }
2754 /* If no test above fails then the indices must be compatible */
2756 }
2758 /*
2759 ** Attempt the transfer optimization on INSERTs of the form
2760 **
2761 ** INSERT INTO tab1 SELECT * FROM tab2;
2762 **
2763 ** The xfer optimization transfers raw records from tab2 over to tab1.
2764 ** Columns are not decoded and reassembled, which greatly improves
2765 ** performance. Raw index records are transferred in the same way.
2766 **
2767 ** The xfer optimization is only attempted if tab1 and tab2 are compatible.
2768 ** There are lots of rules for determining compatibility - see comments
2769 ** embedded in the code for details.
2770 **
2771 ** This routine returns TRUE if the optimization is guaranteed to be used.
2772 ** Sometimes the xfer optimization will only work if the destination table
2773 ** is empty - a factor that can only be determined at run-time. In that
2774 ** case, this routine generates code for the xfer optimization but also
2775 ** does a test to see if the destination table is empty and jumps over the
2776 ** xfer optimization code if the test fails. In that case, this routine
2777 ** returns FALSE so that the caller will know to go ahead and generate
2778 ** an unoptimized transfer. This routine also returns FALSE if there
2779 ** is no chance that the xfer optimization can be applied.
2780 **
2781 ** This optimization is particularly useful at making VACUUM run faster.
2782 */
2789 ){
2808 /* Do not attempt to process this query if there are an WITH clauses
2809 ** attached to it. Proceeding may generate a false "no such table: xxx"
2810 ** error if pSelect reads from a CTE named "xxx". */
2812 }
2813 #ifndef SQLITE_OMIT_VIRTUALTABLE
2816 }
2817 #endif
2821 }
2825 }
2828 }
2831 }
2834 }
2835 /* Do not need to test for a HAVING clause. If HAVING is present but
2836 ** there is no ORDER BY, we will get an error. */
2839 }
2842 }
2845 }
2848 }
2853 }
2857 }
2859 /* At this point we have established that the statement is of the
2860 ** correct syntactic form to participate in this optimization. Now
2861 ** we have to check the semantics.
2862 */
2867 }
2871 }
2874 }
2877 }
2880 }
2883 }
2886 }
2890 #ifdef SQLITE_ENABLE_HIDDEN_COLUMNS
2893 ){
2895 }
2896 #endif
2897 #ifndef SQLITE_OMIT_GENERATED_COLUMNS
2898 /* Even if tables t1 and t2 have identical schemas, if they contain
2899 ** generated columns, then this statement is semantically incorrect:
2900 **
2901 ** INSERT INTO t2 SELECT * FROM t1;
2902 **
2903 ** The reason is that generated column values are returned by the
2904 ** the SELECT statement on the right but the INSERT statement on the
2905 ** left wants them to be omitted.
2906 **
2907 ** Nevertheless, this is a useful notational shorthand to tell SQLite
2908 ** to do a bulk transfer all of the content from t1 over to t2.
2909 **
2910 ** We could, in theory, disable this (except for internal use by the
2911 ** VACUUM command where it is actually needed). But why do that? It
2912 ** seems harmless enough, and provides a useful service.
2913 */
2917 }
2918 /* But the transfer is only allowed if both the source and destination
2919 ** tables have the exact same expressions for generated columns.
2920 ** This requirement could be relaxed for VIRTUAL columns, I suppose.
2921 */
2929 }
2930 }
2931 #endif
2934 }
2938 }
2941 }
2942 /* Default values for second and subsequent columns need to match. */
2953 ){
2955 }
2956 }
2957 }
2961 }
2964 }
2967 }
2970 /* The sqlite3FaultSim() call allows this corruption test to be
2971 ** bypassed during testing, in order to exercise other corruption tests
2972 ** further downstream. */
2974 }
2975 }
2976 #ifndef SQLITE_OMIT_CHECK
2979 }
2980 #endif
2981 #ifndef SQLITE_OMIT_FOREIGN_KEY
2982 /* Disallow the transfer optimization if the destination table constains
2983 ** any foreign key constraints. This is more restrictive than necessary.
2984 ** But the main beneficiary of the transfer optimization is the VACUUM
2985 ** command, and the VACUUM command disables foreign key constraints. So
2986 ** the extra complication to make this rule less restrictive is probably
2987 ** not worth the effort. Ticket [6284df89debdfa61db8073e062908af0c9b6118e]
2988 */
2992 }
2993 #endif
2996 }
2998 /* If we get this far, it means that the xfer optimization is at
2999 ** least a possibility, though it might only work if the destination
3000 ** table (tab1) is initially empty.
3001 */
3002 #ifdef SQLITE_TEST
3003 sqlite3_xferopt_count++;
3004 #endif
3020 )){
3021 /* In some circumstances, we are able to run the xfer optimization
3022 ** only if the destination table is initially empty. Unless the
3023 ** DBFLAG_Vacuum flag is set, this block generates code to make
3024 ** that determination. If DBFLAG_Vacuum is set, then the destination
3025 ** table is always empty.
3026 **
3027 ** Conditions under which the destination must be empty:
3028 **
3029 ** (1) There is no INTEGER PRIMARY KEY but there are indices.
3030 ** (If the destination is not initially empty, the rowid fields
3031 ** of index entries might need to change.)
3032 **
3033 ** (2) The destination has a unique index. (The xfer optimization
3034 ** is unable to test uniqueness.)
3035 **
3036 ** (3) onError is something other than OE_Abort and OE_Rollback.
3037 */
3041 }
3043 u8 insFlags;
3054 }
3061 }
3068 }
3069 #ifdef SQLITE_ENABLE_PREUPDATE_HOOK
3074 #endif
3075 {
3077 }
3081 }
3090 }
3095 }
3106 /* This INSERT command is part of a VACUUM operation, which guarantees
3107 ** that the destination table is empty. If all indexed columns use
3108 ** collation sequence BINARY, then it can also be assumed that the
3109 ** index will be populated by inserting keys in strictly sorted
3110 ** order. In this case, instead of seeking within the b-tree as part
3111 ** of every OP_IdxInsert opcode, an OP_SeekEnd is added before the
3112 ** OP_IdxInsert to seek to the point within the b-tree where each key
3113 ** should be inserted. This is faster.
3114 **
3115 ** If any of the indexed columns use a collation sequence other than
3116 ** BINARY, this optimization is disabled. This is because the user
3117 ** might change the definition of a collation sequence and then run
3118 ** a VACUUM command. In that case keys may not be written in strictly
3119 ** sorted order. */
3123 }
3128 }
3131 }
3137 ){
3139 }
3140 }
3147 }
3159 }
3160 }