LCOV - code coverage report
Current view: top level - src/backend/access/common - attmap.c (source / functions) Hit Total Coverage
Test: PostgreSQL 17beta1 Lines: 93 96 96.9 %
Date: 2024-05-29 11:10:47 Functions: 6 6 100.0 %
Legend: Lines: hit not hit

          Line data    Source code
       1             : /*-------------------------------------------------------------------------
       2             :  *
       3             :  * attmap.c
       4             :  *    Attribute mapping support.
       5             :  *
       6             :  * This file provides utility routines to build and manage attribute
       7             :  * mappings by comparing input and output TupleDescs.  Such mappings
       8             :  * are typically used by DDL operating on inheritance and partition trees
       9             :  * to do a conversion between rowtypes logically equivalent but with
      10             :  * columns in a different order, taking into account dropped columns.
      11             :  * They are also used by the tuple conversion routines in tupconvert.c.
      12             :  *
      13             :  * Portions Copyright (c) 1996-2024, PostgreSQL Global Development Group
      14             :  * Portions Copyright (c) 1994, Regents of the University of California
      15             :  *
      16             :  *
      17             :  * IDENTIFICATION
      18             :  *    src/backend/access/common/attmap.c
      19             :  *
      20             :  *-------------------------------------------------------------------------
      21             :  */
      22             : 
      23             : #include "postgres.h"
      24             : 
      25             : #include "access/attmap.h"
      26             : #include "utils/builtins.h"
      27             : 
      28             : 
      29             : static bool check_attrmap_match(TupleDesc indesc,
      30             :                                 TupleDesc outdesc,
      31             :                                 AttrMap *attrMap);
      32             : 
      33             : /*
      34             :  * make_attrmap
      35             :  *
      36             :  * Utility routine to allocate an attribute map in the current memory
      37             :  * context.
      38             :  */
      39             : AttrMap *
      40       59046 : make_attrmap(int maplen)
      41             : {
      42             :     AttrMap    *res;
      43             : 
      44       59046 :     res = (AttrMap *) palloc0(sizeof(AttrMap));
      45       59046 :     res->maplen = maplen;
      46       59046 :     res->attnums = (AttrNumber *) palloc0(sizeof(AttrNumber) * maplen);
      47       59046 :     return res;
      48             : }
      49             : 
      50             : /*
      51             :  * free_attrmap
      52             :  *
      53             :  * Utility routine to release an attribute map.
      54             :  */
      55             : void
      56       34296 : free_attrmap(AttrMap *map)
      57             : {
      58       34296 :     pfree(map->attnums);
      59       34296 :     pfree(map);
      60       34296 : }
      61             : 
      62             : /*
      63             :  * build_attrmap_by_position
      64             :  *
      65             :  * Return a palloc'd bare attribute map for tuple conversion, matching input
      66             :  * and output columns by position.  Dropped columns are ignored in both input
      67             :  * and output, marked as 0.  This is normally a subroutine for
      68             :  * convert_tuples_by_position in tupconvert.c, but it can be used standalone.
      69             :  *
      70             :  * Note: the errdetail messages speak of indesc as the "returned" rowtype,
      71             :  * outdesc as the "expected" rowtype.  This is okay for current uses but
      72             :  * might need generalization in future.
      73             :  */
      74             : AttrMap *
      75        9524 : build_attrmap_by_position(TupleDesc indesc,
      76             :                           TupleDesc outdesc,
      77             :                           const char *msg)
      78             : {
      79             :     AttrMap    *attrMap;
      80             :     int         nincols;
      81             :     int         noutcols;
      82             :     int         n;
      83             :     int         i;
      84             :     int         j;
      85             :     bool        same;
      86             : 
      87             :     /*
      88             :      * The length is computed as the number of attributes of the expected
      89             :      * rowtype as it includes dropped attributes in its count.
      90             :      */
      91        9524 :     n = outdesc->natts;
      92        9524 :     attrMap = make_attrmap(n);
      93             : 
      94        9524 :     j = 0;                      /* j is next physical input attribute */
      95        9524 :     nincols = noutcols = 0;     /* these count non-dropped attributes */
      96        9524 :     same = true;
      97       34508 :     for (i = 0; i < n; i++)
      98             :     {
      99       25002 :         Form_pg_attribute att = TupleDescAttr(outdesc, i);
     100             :         Oid         atttypid;
     101             :         int32       atttypmod;
     102             : 
     103       25002 :         if (att->attisdropped)
     104         148 :             continue;           /* attrMap->attnums[i] is already 0 */
     105       24854 :         noutcols++;
     106       24854 :         atttypid = att->atttypid;
     107       24854 :         atttypmod = att->atttypmod;
     108       24872 :         for (; j < indesc->natts; j++)
     109             :         {
     110       24864 :             att = TupleDescAttr(indesc, j);
     111       24864 :             if (att->attisdropped)
     112          18 :                 continue;
     113       24846 :             nincols++;
     114             : 
     115             :             /* Found matching column, now check type */
     116       24846 :             if (atttypid != att->atttypid ||
     117       24828 :                 (atttypmod != att->atttypmod && atttypmod >= 0))
     118          18 :                 ereport(ERROR,
     119             :                         (errcode(ERRCODE_DATATYPE_MISMATCH),
     120             :                          errmsg_internal("%s", _(msg)),
     121             :                          errdetail("Returned type %s does not match expected type %s in column %d.",
     122             :                                    format_type_with_typemod(att->atttypid,
     123             :                                                             att->atttypmod),
     124             :                                    format_type_with_typemod(atttypid,
     125             :                                                             atttypmod),
     126             :                                    noutcols)));
     127       24828 :             attrMap->attnums[i] = (AttrNumber) (j + 1);
     128       24828 :             j++;
     129       24828 :             break;
     130             :         }
     131       24836 :         if (attrMap->attnums[i] == 0)
     132           8 :             same = false;       /* we'll complain below */
     133             :     }
     134             : 
     135             :     /* Check for unused input columns */
     136        9512 :     for (; j < indesc->natts; j++)
     137             :     {
     138           6 :         if (TupleDescAttr(indesc, j)->attisdropped)
     139           0 :             continue;
     140           6 :         nincols++;
     141           6 :         same = false;           /* we'll complain below */
     142             :     }
     143             : 
     144             :     /* Report column count mismatch using the non-dropped-column counts */
     145        9506 :     if (!same)
     146          14 :         ereport(ERROR,
     147             :                 (errcode(ERRCODE_DATATYPE_MISMATCH),
     148             :                  errmsg_internal("%s", _(msg)),
     149             :                  errdetail("Number of returned columns (%d) does not match "
     150             :                            "expected column count (%d).",
     151             :                            nincols, noutcols)));
     152             : 
     153             :     /* Check if the map has a one-to-one match */
     154        9492 :     if (check_attrmap_match(indesc, outdesc, attrMap))
     155             :     {
     156             :         /* Runtime conversion is not needed */
     157        9398 :         free_attrmap(attrMap);
     158        9398 :         return NULL;
     159             :     }
     160             : 
     161          94 :     return attrMap;
     162             : }
     163             : 
     164             : /*
     165             :  * build_attrmap_by_name
     166             :  *
     167             :  * Return a palloc'd bare attribute map for tuple conversion, matching input
     168             :  * and output columns by name.  (Dropped columns are ignored in both input and
     169             :  * output.)  This is normally a subroutine for convert_tuples_by_name in
     170             :  * tupconvert.c, but can be used standalone.
     171             :  *
     172             :  * If 'missing_ok' is true, a column from 'outdesc' not being present in
     173             :  * 'indesc' is not flagged as an error; AttrMap.attnums[] entry for such an
     174             :  * outdesc column will be 0 in that case.
     175             :  */
     176             : AttrMap *
     177       38474 : build_attrmap_by_name(TupleDesc indesc,
     178             :                       TupleDesc outdesc,
     179             :                       bool missing_ok)
     180             : {
     181             :     AttrMap    *attrMap;
     182             :     int         outnatts;
     183             :     int         innatts;
     184             :     int         i;
     185       38474 :     int         nextindesc = -1;
     186             : 
     187       38474 :     outnatts = outdesc->natts;
     188       38474 :     innatts = indesc->natts;
     189             : 
     190       38474 :     attrMap = make_attrmap(outnatts);
     191      135250 :     for (i = 0; i < outnatts; i++)
     192             :     {
     193       96776 :         Form_pg_attribute outatt = TupleDescAttr(outdesc, i);
     194             :         char       *attname;
     195             :         Oid         atttypid;
     196             :         int32       atttypmod;
     197             :         int         j;
     198             : 
     199       96776 :         if (outatt->attisdropped)
     200        3628 :             continue;           /* attrMap->attnums[i] is already 0 */
     201       93148 :         attname = NameStr(outatt->attname);
     202       93148 :         atttypid = outatt->atttypid;
     203       93148 :         atttypmod = outatt->atttypmod;
     204             : 
     205             :         /*
     206             :          * Now search for an attribute with the same name in the indesc. It
     207             :          * seems likely that a partitioned table will have the attributes in
     208             :          * the same order as the partition, so the search below is optimized
     209             :          * for that case.  It is possible that columns are dropped in one of
     210             :          * the relations, but not the other, so we use the 'nextindesc'
     211             :          * counter to track the starting point of the search.  If the inner
     212             :          * loop encounters dropped columns then it will have to skip over
     213             :          * them, but it should leave 'nextindesc' at the correct position for
     214             :          * the next outer loop.
     215             :          */
     216      111366 :         for (j = 0; j < innatts; j++)
     217             :         {
     218             :             Form_pg_attribute inatt;
     219             : 
     220      111328 :             nextindesc++;
     221      111328 :             if (nextindesc >= innatts)
     222        5612 :                 nextindesc = 0;
     223             : 
     224      111328 :             inatt = TupleDescAttr(indesc, nextindesc);
     225      111328 :             if (inatt->attisdropped)
     226        3394 :                 continue;
     227      107934 :             if (strcmp(attname, NameStr(inatt->attname)) == 0)
     228             :             {
     229             :                 /* Found it, check type */
     230       93110 :                 if (atttypid != inatt->atttypid || atttypmod != inatt->atttypmod)
     231           0 :                     ereport(ERROR,
     232             :                             (errcode(ERRCODE_DATATYPE_MISMATCH),
     233             :                              errmsg("could not convert row type"),
     234             :                              errdetail("Attribute \"%s\" of type %s does not match corresponding attribute of type %s.",
     235             :                                        attname,
     236             :                                        format_type_be(outdesc->tdtypeid),
     237             :                                        format_type_be(indesc->tdtypeid))));
     238       93110 :                 attrMap->attnums[i] = inatt->attnum;
     239       93110 :                 break;
     240             :             }
     241             :         }
     242       93148 :         if (attrMap->attnums[i] == 0 && !missing_ok)
     243           0 :             ereport(ERROR,
     244             :                     (errcode(ERRCODE_DATATYPE_MISMATCH),
     245             :                      errmsg("could not convert row type"),
     246             :                      errdetail("Attribute \"%s\" of type %s does not exist in type %s.",
     247             :                                attname,
     248             :                                format_type_be(outdesc->tdtypeid),
     249             :                                format_type_be(indesc->tdtypeid))));
     250             :     }
     251       38474 :     return attrMap;
     252             : }
     253             : 
     254             : /*
     255             :  * build_attrmap_by_name_if_req
     256             :  *
     257             :  * Returns mapping created by build_attrmap_by_name, or NULL if no
     258             :  * conversion is required.  This is a convenience routine for
     259             :  * convert_tuples_by_name() in tupconvert.c and other functions, but it
     260             :  * can be used standalone.
     261             :  */
     262             : AttrMap *
     263       16108 : build_attrmap_by_name_if_req(TupleDesc indesc,
     264             :                              TupleDesc outdesc,
     265             :                              bool missing_ok)
     266             : {
     267             :     AttrMap    *attrMap;
     268             : 
     269             :     /* Verify compatibility and prepare attribute-number map */
     270       16108 :     attrMap = build_attrmap_by_name(indesc, outdesc, missing_ok);
     271             : 
     272             :     /* Check if the map has a one-to-one match */
     273       16108 :     if (check_attrmap_match(indesc, outdesc, attrMap))
     274             :     {
     275             :         /* Runtime conversion is not needed */
     276       13110 :         free_attrmap(attrMap);
     277       13110 :         return NULL;
     278             :     }
     279             : 
     280        2998 :     return attrMap;
     281             : }
     282             : 
     283             : /*
     284             :  * check_attrmap_match
     285             :  *
     286             :  * Check to see if the map is a one-to-one match, in which case we need
     287             :  * not to do a tuple conversion, and the attribute map is not necessary.
     288             :  */
     289             : static bool
     290       25600 : check_attrmap_match(TupleDesc indesc,
     291             :                     TupleDesc outdesc,
     292             :                     AttrMap *attrMap)
     293             : {
     294             :     int         i;
     295             : 
     296             :     /* no match if attribute numbers are not the same */
     297       25600 :     if (indesc->natts != outdesc->natts)
     298        1372 :         return false;
     299             : 
     300       81928 :     for (i = 0; i < attrMap->maplen; i++)
     301             :     {
     302       59420 :         Form_pg_attribute inatt = TupleDescAttr(indesc, i);
     303       59420 :         Form_pg_attribute outatt = TupleDescAttr(outdesc, i);
     304             : 
     305             :         /*
     306             :          * If the input column has a missing attribute, we need a conversion.
     307             :          */
     308       59420 :         if (inatt->atthasmissing)
     309          48 :             return false;
     310             : 
     311       59372 :         if (attrMap->attnums[i] == (i + 1))
     312       57642 :             continue;
     313             : 
     314             :         /*
     315             :          * If it's a dropped column and the corresponding input column is also
     316             :          * dropped, we don't need a conversion.  However, attlen and attalign
     317             :          * must agree.
     318             :          */
     319        1730 :         if (attrMap->attnums[i] == 0 &&
     320          90 :             inatt->attisdropped &&
     321          58 :             inatt->attlen == outatt->attlen &&
     322          58 :             inatt->attalign == outatt->attalign)
     323          58 :             continue;
     324             : 
     325        1672 :         return false;
     326             :     }
     327             : 
     328       22508 :     return true;
     329             : }

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