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) 1996-2023, 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 "access/htup_details.h"
27 : #include "utils/builtins.h"
28 :
29 :
30 : static bool check_attrmap_match(TupleDesc indesc,
31 : TupleDesc outdesc,
32 : AttrMap *attrMap);
33 :
34 : /*
35 : * make_attrmap
36 : *
37 : * Utility routine to allocate an attribute map in the current memory
38 : * context.
39 : */
40 : AttrMap *
41 51886 : make_attrmap(int maplen)
42 : {
43 : AttrMap *res;
44 :
45 51886 : res = (AttrMap *) palloc0(sizeof(AttrMap));
46 51886 : res->maplen = maplen;
47 51886 : res->attnums = (AttrNumber *) palloc0(sizeof(AttrNumber) * maplen);
48 51886 : return res;
49 : }
50 :
51 : /*
52 : * free_attrmap
53 : *
54 : * Utility routine to release an attribute map.
55 : */
56 : void
57 30736 : free_attrmap(AttrMap *map)
58 : {
59 30736 : pfree(map->attnums);
60 30736 : pfree(map);
61 30736 : }
62 :
63 : /*
64 : * build_attrmap_by_position
65 : *
66 : * Return a palloc'd bare attribute map for tuple conversion, matching input
67 : * and output columns by position. Dropped columns are ignored in both input
68 : * and output, marked as 0. This is normally a subroutine for
69 : * convert_tuples_by_position in tupconvert.c, but it can be used standalone.
70 : *
71 : * Note: the errdetail messages speak of indesc as the "returned" rowtype,
72 : * outdesc as the "expected" rowtype. This is okay for current uses but
73 : * might need generalization in future.
74 : */
75 : AttrMap *
76 9500 : build_attrmap_by_position(TupleDesc indesc,
77 : TupleDesc outdesc,
78 : const char *msg)
79 : {
80 : AttrMap *attrMap;
81 : int nincols;
82 : int noutcols;
83 : int n;
84 : int i;
85 : int j;
86 : bool same;
87 :
88 : /*
89 : * The length is computed as the number of attributes of the expected
90 : * rowtype as it includes dropped attributes in its count.
91 : */
92 9500 : n = outdesc->natts;
93 9500 : attrMap = make_attrmap(n);
94 :
95 9500 : j = 0; /* j is next physical input attribute */
96 9500 : nincols = noutcols = 0; /* these count non-dropped attributes */
97 9500 : same = true;
98 34418 : for (i = 0; i < n; i++)
99 : {
100 24936 : Form_pg_attribute att = TupleDescAttr(outdesc, i);
101 : Oid atttypid;
102 : int32 atttypmod;
103 :
104 24936 : if (att->attisdropped)
105 148 : continue; /* attrMap->attnums[i] is already 0 */
106 24788 : noutcols++;
107 24788 : atttypid = att->atttypid;
108 24788 : atttypmod = att->atttypmod;
109 24806 : for (; j < indesc->natts; j++)
110 : {
111 24798 : att = TupleDescAttr(indesc, j);
112 24798 : if (att->attisdropped)
113 18 : continue;
114 24780 : nincols++;
115 :
116 : /* Found matching column, now check type */
117 24780 : if (atttypid != att->atttypid ||
118 24762 : (atttypmod != att->atttypmod && atttypmod >= 0))
119 18 : ereport(ERROR,
120 : (errcode(ERRCODE_DATATYPE_MISMATCH),
121 : errmsg_internal("%s", _(msg)),
122 : errdetail("Returned type %s does not match expected type %s in column %d.",
123 : format_type_with_typemod(att->atttypid,
124 : att->atttypmod),
125 : format_type_with_typemod(atttypid,
126 : atttypmod),
127 : noutcols)));
128 24762 : attrMap->attnums[i] = (AttrNumber) (j + 1);
129 24762 : j++;
130 24762 : break;
131 : }
132 24770 : if (attrMap->attnums[i] == 0)
133 8 : same = false; /* we'll complain below */
134 : }
135 :
136 : /* Check for unused input columns */
137 9488 : for (; j < indesc->natts; j++)
138 : {
139 6 : if (TupleDescAttr(indesc, j)->attisdropped)
140 0 : continue;
141 6 : nincols++;
142 6 : same = false; /* we'll complain below */
143 : }
144 :
145 : /* Report column count mismatch using the non-dropped-column counts */
146 9482 : if (!same)
147 14 : ereport(ERROR,
148 : (errcode(ERRCODE_DATATYPE_MISMATCH),
149 : errmsg_internal("%s", _(msg)),
150 : errdetail("Number of returned columns (%d) does not match "
151 : "expected column count (%d).",
152 : nincols, noutcols)));
153 :
154 : /* Check if the map has a one-to-one match */
155 9468 : if (check_attrmap_match(indesc, outdesc, attrMap))
156 : {
157 : /* Runtime conversion is not needed */
158 9374 : free_attrmap(attrMap);
159 9374 : return NULL;
160 : }
161 :
162 94 : return attrMap;
163 : }
164 :
165 : /*
166 : * build_attrmap_by_name
167 : *
168 : * Return a palloc'd bare attribute map for tuple conversion, matching input
169 : * and output columns by name. (Dropped columns are ignored in both input and
170 : * output.) This is normally a subroutine for convert_tuples_by_name in
171 : * tupconvert.c, but can be used standalone.
172 : *
173 : * If 'missing_ok' is true, a column from 'outdesc' not being present in
174 : * 'indesc' is not flagged as an error; AttrMap.attnums[] entry for such an
175 : * outdesc column will be 0 in that case.
176 : */
177 : AttrMap *
178 32614 : build_attrmap_by_name(TupleDesc indesc,
179 : TupleDesc outdesc,
180 : bool missing_ok)
181 : {
182 : AttrMap *attrMap;
183 : int outnatts;
184 : int innatts;
185 : int i;
186 32614 : int nextindesc = -1;
187 :
188 32614 : outnatts = outdesc->natts;
189 32614 : innatts = indesc->natts;
190 :
191 32614 : attrMap = make_attrmap(outnatts);
192 110444 : for (i = 0; i < outnatts; i++)
193 : {
194 77830 : Form_pg_attribute outatt = TupleDescAttr(outdesc, i);
195 : char *attname;
196 : Oid atttypid;
197 : int32 atttypmod;
198 : int j;
199 :
200 77830 : if (outatt->attisdropped)
201 3552 : continue; /* attrMap->attnums[i] is already 0 */
202 74278 : attname = NameStr(outatt->attname);
203 74278 : atttypid = outatt->atttypid;
204 74278 : atttypmod = outatt->atttypmod;
205 :
206 : /*
207 : * Now search for an attribute with the same name in the indesc. It
208 : * seems likely that a partitioned table will have the attributes in
209 : * the same order as the partition, so the search below is optimized
210 : * for that case. It is possible that columns are dropped in one of
211 : * the relations, but not the other, so we use the 'nextindesc'
212 : * counter to track the starting point of the search. If the inner
213 : * loop encounters dropped columns then it will have to skip over
214 : * them, but it should leave 'nextindesc' at the correct position for
215 : * the next outer loop.
216 : */
217 92054 : for (j = 0; j < innatts; j++)
218 : {
219 : Form_pg_attribute inatt;
220 :
221 92016 : nextindesc++;
222 92016 : if (nextindesc >= innatts)
223 5498 : nextindesc = 0;
224 :
225 92016 : inatt = TupleDescAttr(indesc, nextindesc);
226 92016 : if (inatt->attisdropped)
227 3168 : continue;
228 88848 : if (strcmp(attname, NameStr(inatt->attname)) == 0)
229 : {
230 : /* Found it, check type */
231 74240 : if (atttypid != inatt->atttypid || atttypmod != inatt->atttypmod)
232 0 : ereport(ERROR,
233 : (errcode(ERRCODE_DATATYPE_MISMATCH),
234 : errmsg("could not convert row type"),
235 : errdetail("Attribute \"%s\" of type %s does not match corresponding attribute of type %s.",
236 : attname,
237 : format_type_be(outdesc->tdtypeid),
238 : format_type_be(indesc->tdtypeid))));
239 74240 : attrMap->attnums[i] = inatt->attnum;
240 74240 : break;
241 : }
242 : }
243 74278 : if (attrMap->attnums[i] == 0 && !missing_ok)
244 0 : ereport(ERROR,
245 : (errcode(ERRCODE_DATATYPE_MISMATCH),
246 : errmsg("could not convert row type"),
247 : errdetail("Attribute \"%s\" of type %s does not exist in type %s.",
248 : attname,
249 : format_type_be(outdesc->tdtypeid),
250 : format_type_be(indesc->tdtypeid))));
251 : }
252 32614 : return attrMap;
253 : }
254 :
255 : /*
256 : * build_attrmap_by_name_if_req
257 : *
258 : * Returns mapping created by build_attrmap_by_name, or NULL if no
259 : * conversion is required. This is a convenience routine for
260 : * convert_tuples_by_name() in tupconvert.c and other functions, but it
261 : * can be used standalone.
262 : */
263 : AttrMap *
264 13950 : build_attrmap_by_name_if_req(TupleDesc indesc,
265 : TupleDesc outdesc,
266 : bool missing_ok)
267 : {
268 : AttrMap *attrMap;
269 :
270 : /* Verify compatibility and prepare attribute-number map */
271 13950 : attrMap = build_attrmap_by_name(indesc, outdesc, missing_ok);
272 :
273 : /* Check if the map has a one-to-one match */
274 13950 : if (check_attrmap_match(indesc, outdesc, attrMap))
275 : {
276 : /* Runtime conversion is not needed */
277 11058 : free_attrmap(attrMap);
278 11058 : return NULL;
279 : }
280 :
281 2892 : return attrMap;
282 : }
283 :
284 : /*
285 : * check_attrmap_match
286 : *
287 : * Check to see if the map is a one-to-one match, in which case we need
288 : * not to do a tuple conversion, and the attribute map is not necessary.
289 : */
290 : static bool
291 23418 : check_attrmap_match(TupleDesc indesc,
292 : TupleDesc outdesc,
293 : AttrMap *attrMap)
294 : {
295 : int i;
296 :
297 : /* no match if attribute numbers are not the same */
298 23418 : if (indesc->natts != outdesc->natts)
299 1304 : return false;
300 :
301 72394 : for (i = 0; i < attrMap->maplen; i++)
302 : {
303 51962 : Form_pg_attribute inatt = TupleDescAttr(indesc, i);
304 51962 : Form_pg_attribute outatt = TupleDescAttr(outdesc, i);
305 :
306 : /*
307 : * If the input column has a missing attribute, we need a conversion.
308 : */
309 51962 : if (inatt->atthasmissing)
310 48 : return false;
311 :
312 51914 : if (attrMap->attnums[i] == (i + 1))
313 50220 : continue;
314 :
315 : /*
316 : * If it's a dropped column and the corresponding input column is also
317 : * dropped, we don't need a conversion. However, attlen and attalign
318 : * must agree.
319 : */
320 1694 : if (attrMap->attnums[i] == 0 &&
321 92 : inatt->attisdropped &&
322 60 : inatt->attlen == outatt->attlen &&
323 60 : inatt->attalign == outatt->attalign)
324 60 : continue;
325 :
326 1634 : return false;
327 : }
328 :
329 20432 : return true;
330 : }
|
