src/backend/access/common/tupdesc.c

   1 /*-------------------------------------------------------------------------
   2  *
   3  * tupdesc.c
   4  *        POSTGRES tuple descriptor support code
   5  *
   6  * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
   7  * Portions Copyright (c) 1994, Regents of the University of California
   8  *
   9  *
  10  * IDENTIFICATION
  11  *        src/backend/access/common/tupdesc.c
  12  *
  13  * NOTES
  14  *        some of the executor utility code such as "ExecTypeFromTL" should be
  15  *        moved here.
  16  *
  17  *-------------------------------------------------------------------------
  18  */
  19
  20 #include "postgres.h"
  21
  22 #include "access/htup_details.h"
  23 #include "access/toast_compression.h"
  24 #include "access/tupdesc_details.h"
  25 #include "catalog/pg_collation.h"
  26 #include "catalog/pg_type.h"
  27 #include "common/hashfn.h"
  28 #include "utils/builtins.h"
  29 #include "utils/datum.h"
  30 #include "utils/resowner.h"
  31 #include "utils/syscache.h"
  32
  33 /* ResourceOwner callbacks to hold tupledesc references  */
  34 static void ResOwnerReleaseTupleDesc(Datum res);
  35 static char *ResOwnerPrintTupleDesc(Datum res);
  36
  37 static const ResourceOwnerDesc tupdesc_resowner_desc =
  38 {
  39         .name = "tupdesc reference",
  40         .release_phase = RESOURCE_RELEASE_AFTER_LOCKS,
  41         .release_priority = RELEASE_PRIO_TUPDESC_REFS,
  42         .ReleaseResource = ResOwnerReleaseTupleDesc,
  43         .DebugPrint = ResOwnerPrintTupleDesc
  44 };
  45
  46 /* Convenience wrappers over ResourceOwnerRemember/Forget */
  47 static inline void
  48 ResourceOwnerRememberTupleDesc(ResourceOwner owner, TupleDesc tupdesc)
  49 {
  50         ResourceOwnerRemember(owner, PointerGetDatum(tupdesc), &tupdesc_resowner_desc);
  51 }
  52
  53 static inline void
  54 ResourceOwnerForgetTupleDesc(ResourceOwner owner, TupleDesc tupdesc)
  55 {
  56         ResourceOwnerForget(owner, PointerGetDatum(tupdesc), &tupdesc_resowner_desc);
  57 }
  58
  59 /*
  60  * populate_compact_attribute_internal
  61  *              Helper function for populate_compact_attribute()
  62  */
  63 static inline void
  64 populate_compact_attribute_internal(Form_pg_attribute src,
  65                                                                         CompactAttribute *dst)
  66 {
  67         memset(dst, 0, sizeof(CompactAttribute));
  68
  69         dst->attcacheoff = -1;
  70         dst->attlen = src->attlen;
  71
  72         dst->attbyval = src->attbyval;
  73         dst->attispackable = (src->attstorage != TYPSTORAGE_PLAIN);
  74         dst->atthasmissing = src->atthasmissing;
  75         dst->attisdropped = src->attisdropped;
  76         dst->attgenerated = (src->attgenerated != '\0');
  77         dst->attnotnull = src->attnotnull;
  78
  79         switch (src->attalign)
  80         {
  81                 case TYPALIGN_INT:
  82                         dst->attalignby = ALIGNOF_INT;
  83                         break;
  84                 case TYPALIGN_CHAR:
  85                         dst->attalignby = sizeof(char);
  86                         break;
  87                 case TYPALIGN_DOUBLE:
  88                         dst->attalignby = ALIGNOF_DOUBLE;
  89                         break;
  90                 case TYPALIGN_SHORT:
  91                         dst->attalignby = ALIGNOF_SHORT;
  92                         break;
  93                 default:
  94                         dst->attalignby = 0;
  95                         elog(ERROR, "invalid attalign value: %c", src->attalign);
  96                         break;
  97         }
  98 }
  99
 100 /*
 101  * populate_compact_attribute
 102  *              Fill in the corresponding CompactAttribute element from the
 103  *              Form_pg_attribute for the given attribute number.  This must be called
 104  *              whenever a change is made to a Form_pg_attribute in the TupleDesc.
 105  */
 106 void
 107 populate_compact_attribute(TupleDesc tupdesc, int attnum)
 108 {
 109         Form_pg_attribute src = TupleDescAttr(tupdesc, attnum);
 110         CompactAttribute *dst;
 111
 112         /*
 113          * Don't use TupleDescCompactAttr to prevent infinite recursion in assert
 114          * builds.
 115          */
 116         dst = &tupdesc->compact_attrs[attnum];
 117
 118         populate_compact_attribute_internal(src, dst);
 119 }
 120
 121 /*
 122  * verify_compact_attribute
 123  *              In Assert enabled builds, we verify that the CompactAttribute is
 124  *              populated correctly.  This helps find bugs in places such as ALTER
 125  *              TABLE where code makes changes to the FormData_pg_attribute but
 126  *              forgets to call populate_compact_attribute().
 127  *
 128  * This is used in TupleDescCompactAttr(), but declared here to allow access
 129  * to populate_compact_attribute_internal().
 130  */
 131 void
 132 verify_compact_attribute(TupleDesc tupdesc, int attnum)
 133 {
 134 #ifdef USE_ASSERT_CHECKING
 135         CompactAttribute *cattr = &tupdesc->compact_attrs[attnum];
 136         Form_pg_attribute attr = TupleDescAttr(tupdesc, attnum);
 137         CompactAttribute tmp;
 138
 139         /*
 140          * Populate the temporary CompactAttribute from the corresponding
 141          * Form_pg_attribute
 142          */
 143         populate_compact_attribute_internal(attr, &tmp);
 144
 145         /*
 146          * Make the attcacheoff match since it's been reset to -1 by
 147          * populate_compact_attribute_internal.
 148          */
 149         tmp.attcacheoff = cattr->attcacheoff;
 150
 151         /* Check the freshly populated CompactAttribute matches the TupleDesc's */
 152         Assert(memcmp(&tmp, cattr, sizeof(CompactAttribute)) == 0);
 153 #endif
 154 }
 155
 156 /*
 157  * CreateTemplateTupleDesc
 158  *              This function allocates an empty tuple descriptor structure.
 159  *
 160  * Tuple type ID information is initially set for an anonymous record type;
 161  * caller can overwrite this if needed.
 162  */
 163 TupleDesc
 164 CreateTemplateTupleDesc(int natts)
 165 {
 166         TupleDesc       desc;
 167
 168         /*
 169          * sanity checks
 170          */
 171         Assert(natts >= 0);
 172
 173         /*
 174          * Allocate enough memory for the tuple descriptor, the CompactAttribute
 175          * array and also an array of FormData_pg_attribute.
 176          *
 177          * Note: the FormData_pg_attribute array stride is
 178          * sizeof(FormData_pg_attribute), since we declare the array elements as
 179          * FormData_pg_attribute for notational convenience.  However, we only
 180          * guarantee that the first ATTRIBUTE_FIXED_PART_SIZE bytes of each entry
 181          * are valid; most code that copies tupdesc entries around copies just
 182          * that much.  In principle that could be less due to trailing padding,
 183          * although with the current definition of pg_attribute there probably
 184          * isn't any padding.
 185          */
 186         desc = (TupleDesc) palloc(offsetof(struct TupleDescData, compact_attrs) +
 187                                                           natts * sizeof(CompactAttribute) +
 188                                                           natts * sizeof(FormData_pg_attribute));
 189
 190         /*
 191          * Initialize other fields of the tupdesc.
 192          */
 193         desc->natts = natts;
 194         desc->constr = NULL;
 195         desc->tdtypeid = RECORDOID;
 196         desc->tdtypmod = -1;
 197         desc->tdrefcount = -1;          /* assume not reference-counted */
 198
 199         return desc;
 200 }
 201
 202 /*
 203  * CreateTupleDesc
 204  *              This function allocates a new TupleDesc by copying a given
 205  *              Form_pg_attribute array.
 206  *
 207  * Tuple type ID information is initially set for an anonymous record type;
 208  * caller can overwrite this if needed.
 209  */
 210 TupleDesc
 211 CreateTupleDesc(int natts, Form_pg_attribute *attrs)
 212 {
 213         TupleDesc       desc;
 214         int                     i;
 215
 216         desc = CreateTemplateTupleDesc(natts);
 217
 218         for (i = 0; i < natts; ++i)
 219         {
 220                 memcpy(TupleDescAttr(desc, i), attrs[i], ATTRIBUTE_FIXED_PART_SIZE);
 221                 populate_compact_attribute(desc, i);
 222         }
 223         return desc;
 224 }
 225
 226 /*
 227  * CreateTupleDescCopy
 228  *              This function creates a new TupleDesc by copying from an existing
 229  *              TupleDesc.
 230  *
 231  * !!! Constraints and defaults are not copied !!!
 232  */
 233 TupleDesc
 234 CreateTupleDescCopy(TupleDesc tupdesc)
 235 {
 236         TupleDesc       desc;
 237         int                     i;
 238
 239         desc = CreateTemplateTupleDesc(tupdesc->natts);
 240
 241         /* Flat-copy the attribute array */
 242         memcpy(TupleDescAttr(desc, 0),
 243                    TupleDescAttr(tupdesc, 0),
 244                    desc->natts * sizeof(FormData_pg_attribute));
 245
 246         /*
 247          * Since we're not copying constraints and defaults, clear fields
 248          * associated with them.
 249          */
 250         for (i = 0; i < desc->natts; i++)
 251         {
 252                 Form_pg_attribute att = TupleDescAttr(desc, i);
 253
 254                 att->attnotnull = false;
 255                 att->atthasdef = false;
 256                 att->atthasmissing = false;
 257                 att->attidentity = '\0';
 258                 att->attgenerated = '\0';
 259
 260                 populate_compact_attribute(desc, i);
 261         }
 262
 263         /* We can copy the tuple type identification, too */
 264         desc->tdtypeid = tupdesc->tdtypeid;
 265         desc->tdtypmod = tupdesc->tdtypmod;
 266
 267         return desc;
 268 }
 269
 270 /*
 271  * CreateTupleDescTruncatedCopy
 272  *              This function creates a new TupleDesc with only the first 'natts'
 273  *              attributes from an existing TupleDesc
 274  *
 275  * !!! Constraints and defaults are not copied !!!
 276  */
 277 TupleDesc
 278 CreateTupleDescTruncatedCopy(TupleDesc tupdesc, int natts)
 279 {
 280         TupleDesc       desc;
 281         int                     i;
 282
 283         Assert(natts <= tupdesc->natts);
 284
 285         desc = CreateTemplateTupleDesc(natts);
 286
 287         /* Flat-copy the attribute array */
 288         memcpy(TupleDescAttr(desc, 0),
 289                    TupleDescAttr(tupdesc, 0),
 290                    desc->natts * sizeof(FormData_pg_attribute));
 291
 292         /*
 293          * Since we're not copying constraints and defaults, clear fields
 294          * associated with them.
 295          */
 296         for (i = 0; i < desc->natts; i++)
 297         {
 298                 Form_pg_attribute att = TupleDescAttr(desc, i);
 299
 300                 att->attnotnull = false;
 301                 att->atthasdef = false;
 302                 att->atthasmissing = false;
 303                 att->attidentity = '\0';
 304                 att->attgenerated = '\0';
 305
 306                 populate_compact_attribute(desc, i);
 307         }
 308
 309         /* We can copy the tuple type identification, too */
 310         desc->tdtypeid = tupdesc->tdtypeid;
 311         desc->tdtypmod = tupdesc->tdtypmod;
 312
 313         return desc;
 314 }
 315
 316 /*
 317  * CreateTupleDescCopyConstr
 318  *              This function creates a new TupleDesc by copying from an existing
 319  *              TupleDesc (including its constraints and defaults).
 320  */
 321 TupleDesc
 322 CreateTupleDescCopyConstr(TupleDesc tupdesc)
 323 {
 324         TupleDesc       desc;
 325         TupleConstr *constr = tupdesc->constr;
 326         int                     i;
 327
 328         desc = CreateTemplateTupleDesc(tupdesc->natts);
 329
 330         /* Flat-copy the attribute array */
 331         memcpy(TupleDescAttr(desc, 0),
 332                    TupleDescAttr(tupdesc, 0),
 333                    desc->natts * sizeof(FormData_pg_attribute));
 334
 335         for (i = 0; i < desc->natts; i++)
 336                 populate_compact_attribute(desc, i);
 337
 338         /* Copy the TupleConstr data structure, if any */
 339         if (constr)
 340         {
 341                 TupleConstr *cpy = (TupleConstr *) palloc0(sizeof(TupleConstr));
 342
 343                 cpy->has_not_null = constr->has_not_null;
 344                 cpy->has_generated_stored = constr->has_generated_stored;
 345
 346                 if ((cpy->num_defval = constr->num_defval) > 0)
 347                 {
 348                         cpy->defval = (AttrDefault *) palloc(cpy->num_defval * sizeof(AttrDefault));
 349                         memcpy(cpy->defval, constr->defval, cpy->num_defval * sizeof(AttrDefault));
 350                         for (i = cpy->num_defval - 1; i >= 0; i--)
 351                                 cpy->defval[i].adbin = pstrdup(constr->defval[i].adbin);
 352                 }
 353
 354                 if (constr->missing)
 355                 {
 356                         cpy->missing = (AttrMissing *) palloc(tupdesc->natts * sizeof(AttrMissing));
 357                         memcpy(cpy->missing, constr->missing, tupdesc->natts * sizeof(AttrMissing));
 358                         for (i = tupdesc->natts - 1; i >= 0; i--)
 359                         {
 360                                 if (constr->missing[i].am_present)
 361                                 {
 362                                         CompactAttribute *attr = TupleDescCompactAttr(tupdesc, i);
 363
 364                                         cpy->missing[i].am_value = datumCopy(constr->missing[i].am_value,
 365                                                                                                                  attr->attbyval,
 366                                                                                                                  attr->attlen);
 367                                 }
 368                         }
 369                 }
 370
 371                 if ((cpy->num_check = constr->num_check) > 0)
 372                 {
 373                         cpy->check = (ConstrCheck *) palloc(cpy->num_check * sizeof(ConstrCheck));
 374                         memcpy(cpy->check, constr->check, cpy->num_check * sizeof(ConstrCheck));
 375                         for (i = cpy->num_check - 1; i >= 0; i--)
 376                         {
 377                                 cpy->check[i].ccname = pstrdup(constr->check[i].ccname);
 378                                 cpy->check[i].ccbin = pstrdup(constr->check[i].ccbin);
 379                                 cpy->check[i].ccvalid = constr->check[i].ccvalid;
 380                                 cpy->check[i].ccnoinherit = constr->check[i].ccnoinherit;
 381                         }
 382                 }
 383
 384                 desc->constr = cpy;
 385         }
 386
 387         /* We can copy the tuple type identification, too */
 388         desc->tdtypeid = tupdesc->tdtypeid;
 389         desc->tdtypmod = tupdesc->tdtypmod;
 390
 391         return desc;
 392 }
 393
 394 /*
 395  * TupleDescCopy
 396  *              Copy a tuple descriptor into caller-supplied memory.
 397  *              The memory may be shared memory mapped at any address, and must
 398  *              be sufficient to hold TupleDescSize(src) bytes.
 399  *
 400  * !!! Constraints and defaults are not copied !!!
 401  */
 402 void
 403 TupleDescCopy(TupleDesc dst, TupleDesc src)
 404 {
 405         int                     i;
 406
 407         /* Flat-copy the header and attribute arrays */
 408         memcpy(dst, src, TupleDescSize(src));
 409
 410         /*
 411          * Since we're not copying constraints and defaults, clear fields
 412          * associated with them.
 413          */
 414         for (i = 0; i < dst->natts; i++)
 415         {
 416                 Form_pg_attribute att = TupleDescAttr(dst, i);
 417
 418                 att->attnotnull = false;
 419                 att->atthasdef = false;
 420                 att->atthasmissing = false;
 421                 att->attidentity = '\0';
 422                 att->attgenerated = '\0';
 423
 424                 populate_compact_attribute(dst, i);
 425         }
 426         dst->constr = NULL;
 427
 428         /*
 429          * Also, assume the destination is not to be ref-counted.  (Copying the
 430          * source's refcount would be wrong in any case.)
 431          */
 432         dst->tdrefcount = -1;
 433 }
 434
 435 /*
 436  * TupleDescCopyEntry
 437  *              This function copies a single attribute structure from one tuple
 438  *              descriptor to another.
 439  *
 440  * !!! Constraints and defaults are not copied !!!
 441  */
 442 void
 443 TupleDescCopyEntry(TupleDesc dst, AttrNumber dstAttno,
 444                                    TupleDesc src, AttrNumber srcAttno)
 445 {
 446         Form_pg_attribute dstAtt = TupleDescAttr(dst, dstAttno - 1);
 447         Form_pg_attribute srcAtt = TupleDescAttr(src, srcAttno - 1);
 448
 449         /*
 450          * sanity checks
 451          */
 452         Assert(PointerIsValid(src));
 453         Assert(PointerIsValid(dst));
 454         Assert(srcAttno >= 1);
 455         Assert(srcAttno <= src->natts);
 456         Assert(dstAttno >= 1);
 457         Assert(dstAttno <= dst->natts);
 458
 459         memcpy(dstAtt, srcAtt, ATTRIBUTE_FIXED_PART_SIZE);
 460
 461         dstAtt->attnum = dstAttno;
 462
 463         /* since we're not copying constraints or defaults, clear these */
 464         dstAtt->attnotnull = false;
 465         dstAtt->atthasdef = false;
 466         dstAtt->atthasmissing = false;
 467         dstAtt->attidentity = '\0';
 468         dstAtt->attgenerated = '\0';
 469
 470         populate_compact_attribute(dst, dstAttno - 1);
 471 }
 472
 473 /*
 474  * Free a TupleDesc including all substructure
 475  */
 476 void
 477 FreeTupleDesc(TupleDesc tupdesc)
 478 {
 479         int                     i;
 480
 481         /*
 482          * Possibly this should assert tdrefcount == 0, to disallow explicit
 483          * freeing of un-refcounted tupdescs?
 484          */
 485         Assert(tupdesc->tdrefcount <= 0);
 486
 487         if (tupdesc->constr)
 488         {
 489                 if (tupdesc->constr->num_defval > 0)
 490                 {
 491                         AttrDefault *attrdef = tupdesc->constr->defval;
 492
 493                         for (i = tupdesc->constr->num_defval - 1; i >= 0; i--)
 494                                 pfree(attrdef[i].adbin);
 495                         pfree(attrdef);
 496                 }
 497                 if (tupdesc->constr->missing)
 498                 {
 499                         AttrMissing *attrmiss = tupdesc->constr->missing;
 500
 501                         for (i = tupdesc->natts - 1; i >= 0; i--)
 502                         {
 503                                 if (attrmiss[i].am_present
 504                                         && !TupleDescAttr(tupdesc, i)->attbyval)
 505                                         pfree(DatumGetPointer(attrmiss[i].am_value));
 506                         }
 507                         pfree(attrmiss);
 508                 }
 509                 if (tupdesc->constr->num_check > 0)
 510                 {
 511                         ConstrCheck *check = tupdesc->constr->check;
 512
 513                         for (i = tupdesc->constr->num_check - 1; i >= 0; i--)
 514                         {
 515                                 pfree(check[i].ccname);
 516                                 pfree(check[i].ccbin);
 517                         }
 518                         pfree(check);
 519                 }
 520                 pfree(tupdesc->constr);
 521         }
 522
 523         pfree(tupdesc);
 524 }
 525
 526 /*
 527  * Increment the reference count of a tupdesc, and log the reference in
 528  * CurrentResourceOwner.
 529  *
 530  * Do not apply this to tupdescs that are not being refcounted.  (Use the
 531  * macro PinTupleDesc for tupdescs of uncertain status.)
 532  */
 533 void
 534 IncrTupleDescRefCount(TupleDesc tupdesc)
 535 {
 536         Assert(tupdesc->tdrefcount >= 0);
 537
 538         ResourceOwnerEnlarge(CurrentResourceOwner);
 539         tupdesc->tdrefcount++;
 540         ResourceOwnerRememberTupleDesc(CurrentResourceOwner, tupdesc);
 541 }
 542
 543 /*
 544  * Decrement the reference count of a tupdesc, remove the corresponding
 545  * reference from CurrentResourceOwner, and free the tupdesc if no more
 546  * references remain.
 547  *
 548  * Do not apply this to tupdescs that are not being refcounted.  (Use the
 549  * macro ReleaseTupleDesc for tupdescs of uncertain status.)
 550  */
 551 void
 552 DecrTupleDescRefCount(TupleDesc tupdesc)
 553 {
 554         Assert(tupdesc->tdrefcount > 0);
 555
 556         ResourceOwnerForgetTupleDesc(CurrentResourceOwner, tupdesc);
 557         if (--tupdesc->tdrefcount == 0)
 558                 FreeTupleDesc(tupdesc);
 559 }
 560
 561 /*
 562  * Compare two TupleDesc structures for logical equality
 563  */
 564 bool
 565 equalTupleDescs(TupleDesc tupdesc1, TupleDesc tupdesc2)
 566 {
 567         int                     i,
 568                                 n;
 569
 570         if (tupdesc1->natts != tupdesc2->natts)
 571                 return false;
 572         if (tupdesc1->tdtypeid != tupdesc2->tdtypeid)
 573                 return false;
 574
 575         /* tdtypmod and tdrefcount are not checked */
 576
 577         for (i = 0; i < tupdesc1->natts; i++)
 578         {
 579                 Form_pg_attribute attr1 = TupleDescAttr(tupdesc1, i);
 580                 Form_pg_attribute attr2 = TupleDescAttr(tupdesc2, i);
 581
 582                 /*
 583                  * We do not need to check every single field here: we can disregard
 584                  * attrelid and attnum (which were used to place the row in the attrs
 585                  * array in the first place).  It might look like we could dispense
 586                  * with checking attlen/attbyval/attalign, since these are derived
 587                  * from atttypid; but in the case of dropped columns we must check
 588                  * them (since atttypid will be zero for all dropped columns) and in
 589                  * general it seems safer to check them always.
 590                  *
 591                  * We intentionally ignore atthasmissing, since that's not very
 592                  * relevant in tupdescs, which lack the attmissingval field.
 593                  */
 594                 if (strcmp(NameStr(attr1->attname), NameStr(attr2->attname)) != 0)
 595                         return false;
 596                 if (attr1->atttypid != attr2->atttypid)
 597                         return false;
 598                 if (attr1->attlen != attr2->attlen)
 599                         return false;
 600                 if (attr1->attndims != attr2->attndims)
 601                         return false;
 602                 if (attr1->atttypmod != attr2->atttypmod)
 603                         return false;
 604                 if (attr1->attbyval != attr2->attbyval)
 605                         return false;
 606                 if (attr1->attalign != attr2->attalign)
 607                         return false;
 608                 if (attr1->attstorage != attr2->attstorage)
 609                         return false;
 610                 if (attr1->attcompression != attr2->attcompression)
 611                         return false;
 612                 if (attr1->attnotnull != attr2->attnotnull)
 613                         return false;
 614                 if (attr1->atthasdef != attr2->atthasdef)
 615                         return false;
 616                 if (attr1->attidentity != attr2->attidentity)
 617                         return false;
 618                 if (attr1->attgenerated != attr2->attgenerated)
 619                         return false;
 620                 if (attr1->attisdropped != attr2->attisdropped)
 621                         return false;
 622                 if (attr1->attislocal != attr2->attislocal)
 623                         return false;
 624                 if (attr1->attinhcount != attr2->attinhcount)
 625                         return false;
 626                 if (attr1->attcollation != attr2->attcollation)
 627                         return false;
 628                 /* variable-length fields are not even present... */
 629         }
 630
 631         if (tupdesc1->constr != NULL)
 632         {
 633                 TupleConstr *constr1 = tupdesc1->constr;
 634                 TupleConstr *constr2 = tupdesc2->constr;
 635
 636                 if (constr2 == NULL)
 637                         return false;
 638                 if (constr1->has_not_null != constr2->has_not_null)
 639                         return false;
 640                 if (constr1->has_generated_stored != constr2->has_generated_stored)
 641                         return false;
 642                 n = constr1->num_defval;
 643                 if (n != (int) constr2->num_defval)
 644                         return false;
 645                 /* We assume here that both AttrDefault arrays are in adnum order */
 646                 for (i = 0; i < n; i++)
 647                 {
 648                         AttrDefault *defval1 = constr1->defval + i;
 649                         AttrDefault *defval2 = constr2->defval + i;
 650
 651                         if (defval1->adnum != defval2->adnum)
 652                                 return false;
 653                         if (strcmp(defval1->adbin, defval2->adbin) != 0)
 654                                 return false;
 655                 }
 656                 if (constr1->missing)
 657                 {
 658                         if (!constr2->missing)
 659                                 return false;
 660                         for (i = 0; i < tupdesc1->natts; i++)
 661                         {
 662                                 AttrMissing *missval1 = constr1->missing + i;
 663                                 AttrMissing *missval2 = constr2->missing + i;
 664
 665                                 if (missval1->am_present != missval2->am_present)
 666                                         return false;
 667                                 if (missval1->am_present)
 668                                 {
 669                                         CompactAttribute *missatt1 = TupleDescCompactAttr(tupdesc1, i);
 670
 671                                         if (!datumIsEqual(missval1->am_value, missval2->am_value,
 672                                                                           missatt1->attbyval, missatt1->attlen))
 673                                                 return false;
 674                                 }
 675                         }
 676                 }
 677                 else if (constr2->missing)
 678                         return false;
 679                 n = constr1->num_check;
 680                 if (n != (int) constr2->num_check)
 681                         return false;
 682
 683                 /*
 684                  * Similarly, we rely here on the ConstrCheck entries being sorted by
 685                  * name.  If there are duplicate names, the outcome of the comparison
 686                  * is uncertain, but that should not happen.
 687                  */
 688                 for (i = 0; i < n; i++)
 689                 {
 690                         ConstrCheck *check1 = constr1->check + i;
 691                         ConstrCheck *check2 = constr2->check + i;
 692
 693                         if (!(strcmp(check1->ccname, check2->ccname) == 0 &&
 694                                   strcmp(check1->ccbin, check2->ccbin) == 0 &&
 695                                   check1->ccvalid == check2->ccvalid &&
 696                                   check1->ccnoinherit == check2->ccnoinherit))
 697                                 return false;
 698                 }
 699         }
 700         else if (tupdesc2->constr != NULL)
 701                 return false;
 702         return true;
 703 }
 704
 705 /*
 706  * equalRowTypes
 707  *
 708  * This determines whether two tuple descriptors have equal row types.  This
 709  * only checks those fields in pg_attribute that are applicable for row types,
 710  * while ignoring those fields that define the physical row storage or those
 711  * that define table column metadata.
 712  *
 713  * Specifically, this checks:
 714  *
 715  * - same number of attributes
 716  * - same composite type ID (but could both be zero)
 717  * - corresponding attributes (in order) have same the name, type, typmod,
 718  *   collation
 719  *
 720  * This is used to check whether two record types are compatible, whether
 721  * function return row types are the same, and other similar situations.
 722  *
 723  * (XXX There was some discussion whether attndims should be checked here, but
 724  * for now it has been decided not to.)
 725  *
 726  * Note: We deliberately do not check the tdtypmod field.  This allows
 727  * typcache.c to use this routine to see if a cached record type matches a
 728  * requested type.
 729  */
 730 bool
 731 equalRowTypes(TupleDesc tupdesc1, TupleDesc tupdesc2)
 732 {
 733         if (tupdesc1->natts != tupdesc2->natts)
 734                 return false;
 735         if (tupdesc1->tdtypeid != tupdesc2->tdtypeid)
 736                 return false;
 737
 738         for (int i = 0; i < tupdesc1->natts; i++)
 739         {
 740                 Form_pg_attribute attr1 = TupleDescAttr(tupdesc1, i);
 741                 Form_pg_attribute attr2 = TupleDescAttr(tupdesc2, i);
 742
 743                 if (strcmp(NameStr(attr1->attname), NameStr(attr2->attname)) != 0)
 744                         return false;
 745                 if (attr1->atttypid != attr2->atttypid)
 746                         return false;
 747                 if (attr1->atttypmod != attr2->atttypmod)
 748                         return false;
 749                 if (attr1->attcollation != attr2->attcollation)
 750                         return false;
 751
 752                 /* Record types derived from tables could have dropped fields. */
 753                 if (attr1->attisdropped != attr2->attisdropped)
 754                         return false;
 755         }
 756
 757         return true;
 758 }
 759
 760 /*
 761  * hashRowType
 762  *
 763  * If two tuple descriptors would be considered equal by equalRowTypes()
 764  * then their hash value will be equal according to this function.
 765  */
 766 uint32
 767 hashRowType(TupleDesc desc)
 768 {
 769         uint32          s;
 770         int                     i;
 771
 772         s = hash_combine(0, hash_uint32(desc->natts));
 773         s = hash_combine(s, hash_uint32(desc->tdtypeid));
 774         for (i = 0; i < desc->natts; ++i)
 775                 s = hash_combine(s, hash_uint32(TupleDescAttr(desc, i)->atttypid));
 776
 777         return s;
 778 }
 779
 780 /*
 781  * TupleDescInitEntry
 782  *              This function initializes a single attribute structure in
 783  *              a previously allocated tuple descriptor.
 784  *
 785  * If attributeName is NULL, the attname field is set to an empty string
 786  * (this is for cases where we don't know or need a name for the field).
 787  * Also, some callers use this function to change the datatype-related fields
 788  * in an existing tupdesc; they pass attributeName = NameStr(att->attname)
 789  * to indicate that the attname field shouldn't be modified.
 790  *
 791  * Note that attcollation is set to the default for the specified datatype.
 792  * If a nondefault collation is needed, insert it afterwards using
 793  * TupleDescInitEntryCollation.
 794  */
 795 void
 796 TupleDescInitEntry(TupleDesc desc,
 797                                    AttrNumber attributeNumber,
 798                                    const char *attributeName,
 799                                    Oid oidtypeid,
 800                                    int32 typmod,
 801                                    int attdim)
 802 {
 803         HeapTuple       tuple;
 804         Form_pg_type typeForm;
 805         Form_pg_attribute att;
 806
 807         /*
 808          * sanity checks
 809          */
 810         Assert(PointerIsValid(desc));
 811         Assert(attributeNumber >= 1);
 812         Assert(attributeNumber <= desc->natts);
 813         Assert(attdim >= 0);
 814         Assert(attdim <= PG_INT16_MAX);
 815
 816         /*
 817          * initialize the attribute fields
 818          */
 819         att = TupleDescAttr(desc, attributeNumber - 1);
 820
 821         att->attrelid = 0;                      /* dummy value */
 822
 823         /*
 824          * Note: attributeName can be NULL, because the planner doesn't always
 825          * fill in valid resname values in targetlists, particularly for resjunk
 826          * attributes. Also, do nothing if caller wants to re-use the old attname.
 827          */
 828         if (attributeName == NULL)
 829                 MemSet(NameStr(att->attname), 0, NAMEDATALEN);
 830         else if (attributeName != NameStr(att->attname))
 831                 namestrcpy(&(att->attname), attributeName);
 832
 833         att->atttypmod = typmod;
 834
 835         att->attnum = attributeNumber;
 836         att->attndims = attdim;
 837
 838         att->attnotnull = false;
 839         att->atthasdef = false;
 840         att->atthasmissing = false;
 841         att->attidentity = '\0';
 842         att->attgenerated = '\0';
 843         att->attisdropped = false;
 844         att->attislocal = true;
 845         att->attinhcount = 0;
 846         /* variable-length fields are not present in tupledescs */
 847
 848         tuple = SearchSysCache1(TYPEOID, ObjectIdGetDatum(oidtypeid));
 849         if (!HeapTupleIsValid(tuple))
 850                 elog(ERROR, "cache lookup failed for type %u", oidtypeid);
 851         typeForm = (Form_pg_type) GETSTRUCT(tuple);
 852
 853         att->atttypid = oidtypeid;
 854         att->attlen = typeForm->typlen;
 855         att->attbyval = typeForm->typbyval;
 856         att->attalign = typeForm->typalign;
 857         att->attstorage = typeForm->typstorage;
 858         att->attcompression = InvalidCompressionMethod;
 859         att->attcollation = typeForm->typcollation;
 860
 861         populate_compact_attribute(desc, attributeNumber - 1);
 862
 863         ReleaseSysCache(tuple);
 864 }
 865
 866 /*
 867  * TupleDescInitBuiltinEntry
 868  *              Initialize a tuple descriptor without catalog access.  Only
 869  *              a limited range of builtin types are supported.
 870  */
 871 void
 872 TupleDescInitBuiltinEntry(TupleDesc desc,
 873                                                   AttrNumber attributeNumber,
 874                                                   const char *attributeName,
 875                                                   Oid oidtypeid,
 876                                                   int32 typmod,
 877                                                   int attdim)
 878 {
 879         Form_pg_attribute att;
 880
 881         /* sanity checks */
 882         Assert(PointerIsValid(desc));
 883         Assert(attributeNumber >= 1);
 884         Assert(attributeNumber <= desc->natts);
 885         Assert(attdim >= 0);
 886         Assert(attdim <= PG_INT16_MAX);
 887
 888         /* initialize the attribute fields */
 889         att = TupleDescAttr(desc, attributeNumber - 1);
 890         att->attrelid = 0;                      /* dummy value */
 891
 892         /* unlike TupleDescInitEntry, we require an attribute name */
 893         Assert(attributeName != NULL);
 894         namestrcpy(&(att->attname), attributeName);
 895
 896         att->atttypmod = typmod;
 897
 898         att->attnum = attributeNumber;
 899         att->attndims = attdim;
 900
 901         att->attnotnull = false;
 902         att->atthasdef = false;
 903         att->atthasmissing = false;
 904         att->attidentity = '\0';
 905         att->attgenerated = '\0';
 906         att->attisdropped = false;
 907         att->attislocal = true;
 908         att->attinhcount = 0;
 909         /* variable-length fields are not present in tupledescs */
 910
 911         att->atttypid = oidtypeid;
 912
 913         /*
 914          * Our goal here is to support just enough types to let basic builtin
 915          * commands work without catalog access - e.g. so that we can do certain
 916          * things even in processes that are not connected to a database.
 917          */
 918         switch (oidtypeid)
 919         {
 920                 case TEXTOID:
 921                 case TEXTARRAYOID:
 922                         att->attlen = -1;
 923                         att->attbyval = false;
 924                         att->attalign = TYPALIGN_INT;
 925                         att->attstorage = TYPSTORAGE_EXTENDED;
 926                         att->attcompression = InvalidCompressionMethod;
 927                         att->attcollation = DEFAULT_COLLATION_OID;
 928                         break;
 929
 930                 case BOOLOID:
 931                         att->attlen = 1;
 932                         att->attbyval = true;
 933                         att->attalign = TYPALIGN_CHAR;
 934                         att->attstorage = TYPSTORAGE_PLAIN;
 935                         att->attcompression = InvalidCompressionMethod;
 936                         att->attcollation = InvalidOid;
 937                         break;
 938
 939                 case INT4OID:
 940                         att->attlen = 4;
 941                         att->attbyval = true;
 942                         att->attalign = TYPALIGN_INT;
 943                         att->attstorage = TYPSTORAGE_PLAIN;
 944                         att->attcompression = InvalidCompressionMethod;
 945                         att->attcollation = InvalidOid;
 946                         break;
 947
 948                 case INT8OID:
 949                         att->attlen = 8;
 950                         att->attbyval = FLOAT8PASSBYVAL;
 951                         att->attalign = TYPALIGN_DOUBLE;
 952                         att->attstorage = TYPSTORAGE_PLAIN;
 953                         att->attcompression = InvalidCompressionMethod;
 954                         att->attcollation = InvalidOid;
 955                         break;
 956
 957                 case OIDOID:
 958                         att->attlen = 4;
 959                         att->attbyval = true;
 960                         att->attalign = TYPALIGN_INT;
 961                         att->attstorage = TYPSTORAGE_PLAIN;
 962                         att->attcompression = InvalidCompressionMethod;
 963                         att->attcollation = InvalidOid;
 964                         break;
 965
 966                 default:
 967                         elog(ERROR, "unsupported type %u", oidtypeid);
 968         }
 969
 970         populate_compact_attribute(desc, attributeNumber - 1);
 971 }
 972
 973 /*
 974  * TupleDescInitEntryCollation
 975  *
 976  * Assign a nondefault collation to a previously initialized tuple descriptor
 977  * entry.
 978  */
 979 void
 980 TupleDescInitEntryCollation(TupleDesc desc,
 981                                                         AttrNumber attributeNumber,
 982                                                         Oid collationid)
 983 {
 984         /*
 985          * sanity checks
 986          */
 987         Assert(PointerIsValid(desc));
 988         Assert(attributeNumber >= 1);
 989         Assert(attributeNumber <= desc->natts);
 990
 991         TupleDescAttr(desc, attributeNumber - 1)->attcollation = collationid;
 992 }
 993
 994 /*
 995  * BuildDescFromLists
 996  *
 997  * Build a TupleDesc given lists of column names (as String nodes),
 998  * column type OIDs, typmods, and collation OIDs.
 999  *
1000  * No constraints are generated.
1001  *
1002  * This is for use with functions returning RECORD.
1003  */
1004 TupleDesc
1005 BuildDescFromLists(const List *names, const List *types, const List *typmods, const List *collations)
1006 {
1007         int                     natts;
1008         AttrNumber      attnum;
1009         ListCell   *l1;
1010         ListCell   *l2;
1011         ListCell   *l3;
1012         ListCell   *l4;
1013         TupleDesc       desc;
1014
1015         natts = list_length(names);
1016         Assert(natts == list_length(types));
1017         Assert(natts == list_length(typmods));
1018         Assert(natts == list_length(collations));
1019
1020         /*
1021          * allocate a new tuple descriptor
1022          */
1023         desc = CreateTemplateTupleDesc(natts);
1024
1025         attnum = 0;
1026         forfour(l1, names, l2, types, l3, typmods, l4, collations)
1027         {
1028                 char       *attname = strVal(lfirst(l1));
1029                 Oid                     atttypid = lfirst_oid(l2);
1030                 int32           atttypmod = lfirst_int(l3);
1031                 Oid                     attcollation = lfirst_oid(l4);
1032
1033                 attnum++;
1034
1035                 TupleDescInitEntry(desc, attnum, attname, atttypid, atttypmod, 0);
1036                 TupleDescInitEntryCollation(desc, attnum, attcollation);
1037         }
1038
1039         return desc;
1040 }
1041
1042 /*
1043  * Get default expression (or NULL if none) for the given attribute number.
1044  */
1045 Node *
1046 TupleDescGetDefault(TupleDesc tupdesc, AttrNumber attnum)
1047 {
1048         Node       *result = NULL;
1049
1050         if (tupdesc->constr)
1051         {
1052                 AttrDefault *attrdef = tupdesc->constr->defval;
1053
1054                 for (int i = 0; i < tupdesc->constr->num_defval; i++)
1055                 {
1056                         if (attrdef[i].adnum == attnum)
1057                         {
1058                                 result = stringToNode(attrdef[i].adbin);
1059                                 break;
1060                         }
1061                 }
1062         }
1063
1064         return result;
1065 }
1066
1067 /* ResourceOwner callbacks */
1068
1069 static void
1070 ResOwnerReleaseTupleDesc(Datum res)
1071 {
1072         TupleDesc       tupdesc = (TupleDesc) DatumGetPointer(res);
1073
1074         /* Like DecrTupleDescRefCount, but don't call ResourceOwnerForget() */
1075         Assert(tupdesc->tdrefcount > 0);
1076         if (--tupdesc->tdrefcount == 0)
1077                 FreeTupleDesc(tupdesc);
1078 }
1079
1080 static char *
1081 ResOwnerPrintTupleDesc(Datum res)
1082 {
1083         TupleDesc       tupdesc = (TupleDesc) DatumGetPointer(res);
1084
1085         return psprintf("TupleDesc %p (%u,%d)",
1086                                         tupdesc, tupdesc->tdtypeid, tupdesc->tdtypmod);
1087 }