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) 1996-2025, 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 62398 : make_attrmap(int maplen)
41 : {
42 : AttrMap *res;
43 :
44 62398 : res = (AttrMap *) palloc0(sizeof(AttrMap));
45 62398 : res->maplen = maplen;
46 62398 : res->attnums = (AttrNumber *) palloc0(sizeof(AttrNumber) * maplen);
47 62398 : return res;
48 : }
49 :
50 : /*
51 : * free_attrmap
52 : *
53 : * Utility routine to release an attribute map.
54 : */
55 : void
56 34164 : free_attrmap(AttrMap *map)
57 : {
58 34164 : pfree(map->attnums);
59 34164 : pfree(map);
60 34164 : }
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 9576 : 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 9576 : n = outdesc->natts;
92 9576 : attrMap = make_attrmap(n);
93 :
94 9576 : j = 0; /* j is next physical input attribute */
95 9576 : nincols = noutcols = 0; /* these count non-dropped attributes */
96 9576 : same = true;
97 34702 : for (i = 0; i < n; i++)
98 : {
99 25146 : Form_pg_attribute outatt = TupleDescAttr(outdesc, i);
100 :
101 25146 : if (outatt->attisdropped)
102 152 : continue; /* attrMap->attnums[i] is already 0 */
103 24994 : noutcols++;
104 25012 : for (; j < indesc->natts; j++)
105 : {
106 25004 : Form_pg_attribute inatt = TupleDescAttr(indesc, j);
107 :
108 25004 : if (inatt->attisdropped)
109 18 : continue;
110 24986 : nincols++;
111 :
112 : /* Found matching column, now check type */
113 24986 : if (outatt->atttypid != inatt->atttypid ||
114 24966 : (outatt->atttypmod != inatt->atttypmod && outatt->atttypmod >= 0))
115 20 : ereport(ERROR,
116 : (errcode(ERRCODE_DATATYPE_MISMATCH),
117 : errmsg_internal("%s", _(msg)),
118 : errdetail("Returned type %s does not match expected type %s in column \"%s\" (position %d).",
119 : format_type_with_typemod(inatt->atttypid,
120 : inatt->atttypmod),
121 : format_type_with_typemod(outatt->atttypid,
122 : outatt->atttypmod),
123 : NameStr(outatt->attname),
124 : noutcols)));
125 24966 : attrMap->attnums[i] = (AttrNumber) (j + 1);
126 24966 : j++;
127 24966 : break;
128 : }
129 24974 : if (attrMap->attnums[i] == 0)
130 8 : same = false; /* we'll complain below */
131 : }
132 :
133 : /* Check for unused input columns */
134 9562 : for (; j < indesc->natts; j++)
135 : {
136 6 : if (TupleDescCompactAttr(indesc, j)->attisdropped)
137 0 : continue;
138 6 : nincols++;
139 6 : same = false; /* we'll complain below */
140 : }
141 :
142 : /* Report column count mismatch using the non-dropped-column counts */
143 9556 : if (!same)
144 14 : ereport(ERROR,
145 : (errcode(ERRCODE_DATATYPE_MISMATCH),
146 : errmsg_internal("%s", _(msg)),
147 : errdetail("Number of returned columns (%d) does not match "
148 : "expected column count (%d).",
149 : nincols, noutcols)));
150 :
151 : /* Check if the map has a one-to-one match */
152 9542 : if (check_attrmap_match(indesc, outdesc, attrMap))
153 : {
154 : /* Runtime conversion is not needed */
155 9446 : free_attrmap(attrMap);
156 9446 : return NULL;
157 : }
158 :
159 96 : return attrMap;
160 : }
161 :
162 : /*
163 : * build_attrmap_by_name
164 : *
165 : * Return a palloc'd bare attribute map for tuple conversion, matching input
166 : * and output columns by name. (Dropped columns are ignored in both input and
167 : * output.) This is normally a subroutine for convert_tuples_by_name in
168 : * tupconvert.c, but can be used standalone.
169 : *
170 : * If 'missing_ok' is true, a column from 'outdesc' not being present in
171 : * 'indesc' is not flagged as an error; AttrMap.attnums[] entry for such an
172 : * outdesc column will be 0 in that case.
173 : */
174 : AttrMap *
175 41286 : build_attrmap_by_name(TupleDesc indesc,
176 : TupleDesc outdesc,
177 : bool missing_ok)
178 : {
179 : AttrMap *attrMap;
180 : int outnatts;
181 : int innatts;
182 : int i;
183 41286 : int nextindesc = -1;
184 :
185 41286 : outnatts = outdesc->natts;
186 41286 : innatts = indesc->natts;
187 :
188 41286 : attrMap = make_attrmap(outnatts);
189 139562 : for (i = 0; i < outnatts; i++)
190 : {
191 98276 : Form_pg_attribute outatt = TupleDescAttr(outdesc, i);
192 : char *attname;
193 : Oid atttypid;
194 : int32 atttypmod;
195 : int j;
196 :
197 98276 : if (outatt->attisdropped)
198 4272 : continue; /* attrMap->attnums[i] is already 0 */
199 94004 : attname = NameStr(outatt->attname);
200 94004 : atttypid = outatt->atttypid;
201 94004 : atttypmod = outatt->atttypmod;
202 :
203 : /*
204 : * Now search for an attribute with the same name in the indesc. It
205 : * seems likely that a partitioned table will have the attributes in
206 : * the same order as the partition, so the search below is optimized
207 : * for that case. It is possible that columns are dropped in one of
208 : * the relations, but not the other, so we use the 'nextindesc'
209 : * counter to track the starting point of the search. If the inner
210 : * loop encounters dropped columns then it will have to skip over
211 : * them, but it should leave 'nextindesc' at the correct position for
212 : * the next outer loop.
213 : */
214 114942 : for (j = 0; j < innatts; j++)
215 : {
216 : Form_pg_attribute inatt;
217 :
218 114712 : nextindesc++;
219 114712 : if (nextindesc >= innatts)
220 7034 : nextindesc = 0;
221 :
222 114712 : inatt = TupleDescAttr(indesc, nextindesc);
223 114712 : if (inatt->attisdropped)
224 3682 : continue;
225 111030 : if (strcmp(attname, NameStr(inatt->attname)) == 0)
226 : {
227 : /* Found it, check type */
228 93774 : if (atttypid != inatt->atttypid || atttypmod != inatt->atttypmod)
229 0 : ereport(ERROR,
230 : (errcode(ERRCODE_DATATYPE_MISMATCH),
231 : errmsg("could not convert row type"),
232 : errdetail("Attribute \"%s\" of type %s does not match corresponding attribute of type %s.",
233 : attname,
234 : format_type_be(outdesc->tdtypeid),
235 : format_type_be(indesc->tdtypeid))));
236 93774 : attrMap->attnums[i] = inatt->attnum;
237 93774 : break;
238 : }
239 : }
240 94004 : if (attrMap->attnums[i] == 0 && !missing_ok)
241 0 : ereport(ERROR,
242 : (errcode(ERRCODE_DATATYPE_MISMATCH),
243 : errmsg("could not convert row type"),
244 : errdetail("Attribute \"%s\" of type %s does not exist in type %s.",
245 : attname,
246 : format_type_be(outdesc->tdtypeid),
247 : format_type_be(indesc->tdtypeid))));
248 : }
249 41286 : return attrMap;
250 : }
251 :
252 : /*
253 : * build_attrmap_by_name_if_req
254 : *
255 : * Returns mapping created by build_attrmap_by_name, or NULL if no
256 : * conversion is required. This is a convenience routine for
257 : * convert_tuples_by_name() in tupconvert.c and other functions, but it
258 : * can be used standalone.
259 : */
260 : AttrMap *
261 15614 : build_attrmap_by_name_if_req(TupleDesc indesc,
262 : TupleDesc outdesc,
263 : bool missing_ok)
264 : {
265 : AttrMap *attrMap;
266 :
267 : /* Verify compatibility and prepare attribute-number map */
268 15614 : attrMap = build_attrmap_by_name(indesc, outdesc, missing_ok);
269 :
270 : /* Check if the map has a one-to-one match */
271 15614 : if (check_attrmap_match(indesc, outdesc, attrMap))
272 : {
273 : /* Runtime conversion is not needed */
274 12450 : free_attrmap(attrMap);
275 12450 : return NULL;
276 : }
277 :
278 3164 : return attrMap;
279 : }
280 :
281 : /*
282 : * check_attrmap_match
283 : *
284 : * Check to see if the map is a one-to-one match, in which case we need
285 : * not to do a tuple conversion, and the attribute map is not necessary.
286 : */
287 : static bool
288 25156 : check_attrmap_match(TupleDesc indesc,
289 : TupleDesc outdesc,
290 : AttrMap *attrMap)
291 : {
292 : int i;
293 :
294 : /* no match if attribute numbers are not the same */
295 25156 : if (indesc->natts != outdesc->natts)
296 1454 : return false;
297 :
298 77628 : for (i = 0; i < attrMap->maplen; i++)
299 : {
300 55732 : CompactAttribute *inatt = TupleDescCompactAttr(indesc, i);
301 : CompactAttribute *outatt;
302 :
303 : /*
304 : * If the input column has a missing attribute, we need a conversion.
305 : */
306 55732 : if (inatt->atthasmissing)
307 50 : return false;
308 :
309 55682 : if (attrMap->attnums[i] == (i + 1))
310 53866 : continue;
311 :
312 1816 : outatt = TupleDescCompactAttr(outdesc, i);
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
317 : * attalignby must agree.
318 : */
319 1816 : if (attrMap->attnums[i] == 0 &&
320 92 : inatt->attisdropped &&
321 60 : inatt->attlen == outatt->attlen &&
322 60 : inatt->attalignby == outatt->attalignby)
323 60 : continue;
324 :
325 1756 : return false;
326 : }
327 :
328 21896 : return true;
329 : }
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