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 58296 : make_attrmap(int maplen)
41 : {
42 : AttrMap *res;
43 :
44 58296 : res = (AttrMap *) palloc0(sizeof(AttrMap));
45 58296 : res->maplen = maplen;
46 58296 : res->attnums = (AttrNumber *) palloc0(sizeof(AttrNumber) * maplen);
47 58296 : return res;
48 : }
49 :
50 : /*
51 : * free_attrmap
52 : *
53 : * Utility routine to release an attribute map.
54 : */
55 : void
56 32940 : free_attrmap(AttrMap *map)
57 : {
58 32940 : pfree(map->attnums);
59 32940 : pfree(map);
60 32940 : }
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 37886 : 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 37886 : int nextindesc = -1;
186 :
187 37886 : outnatts = outdesc->natts;
188 37886 : innatts = indesc->natts;
189 :
190 37886 : attrMap = make_attrmap(outnatts);
191 128302 : for (i = 0; i < outnatts; i++)
192 : {
193 90416 : Form_pg_attribute outatt = TupleDescAttr(outdesc, i);
194 : char *attname;
195 : Oid atttypid;
196 : int32 atttypmod;
197 : int j;
198 :
199 90416 : if (outatt->attisdropped)
200 4194 : continue; /* attrMap->attnums[i] is already 0 */
201 86222 : attname = NameStr(outatt->attname);
202 86222 : atttypid = outatt->atttypid;
203 86222 : 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 106194 : for (j = 0; j < innatts; j++)
217 : {
218 : Form_pg_attribute inatt;
219 :
220 106030 : nextindesc++;
221 106030 : if (nextindesc >= innatts)
222 6464 : nextindesc = 0;
223 :
224 106030 : inatt = TupleDescAttr(indesc, nextindesc);
225 106030 : if (inatt->attisdropped)
226 3616 : continue;
227 102414 : if (strcmp(attname, NameStr(inatt->attname)) == 0)
228 : {
229 : /* Found it, check type */
230 86058 : 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 86058 : attrMap->attnums[i] = inatt->attnum;
239 86058 : break;
240 : }
241 : }
242 86222 : 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 37886 : 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 15070 : 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 15070 : attrMap = build_attrmap_by_name(indesc, outdesc, missing_ok);
271 :
272 : /* Check if the map has a one-to-one match */
273 15070 : if (check_attrmap_match(indesc, outdesc, attrMap))
274 : {
275 : /* Runtime conversion is not needed */
276 12050 : free_attrmap(attrMap);
277 12050 : return NULL;
278 : }
279 :
280 3020 : 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 24562 : 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 24562 : if (indesc->natts != outdesc->natts)
298 1378 : return false;
299 :
300 76074 : for (i = 0; i < attrMap->maplen; i++)
301 : {
302 54626 : Form_pg_attribute inatt = TupleDescAttr(indesc, i);
303 54626 : Form_pg_attribute outatt = TupleDescAttr(outdesc, i);
304 :
305 : /*
306 : * If the input column has a missing attribute, we need a conversion.
307 : */
308 54626 : if (inatt->atthasmissing)
309 50 : return false;
310 :
311 54576 : if (attrMap->attnums[i] == (i + 1))
312 52830 : 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 1746 : if (attrMap->attnums[i] == 0 &&
320 92 : inatt->attisdropped &&
321 60 : inatt->attlen == outatt->attlen &&
322 60 : inatt->attalign == outatt->attalign)
323 60 : continue;
324 :
325 1686 : return false;
326 : }
327 :
328 21448 : return true;
329 : }
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