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tupconvert.c
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1 /*-------------------------------------------------------------------------
2  *
3  * tupconvert.c
4  * Tuple conversion support.
5  *
6  * These functions provide conversion between rowtypes that are logically
7  * equivalent but might have columns in a different order or different sets
8  * of dropped columns. There is some overlap of functionality with the
9  * executor's "junkfilter" routines, but these functions work on bare
10  * HeapTuples rather than TupleTableSlots.
11  *
12  * Portions Copyright (c) 1996-2017, PostgreSQL Global Development Group
13  * Portions Copyright (c) 1994, Regents of the University of California
14  *
15  *
16  * IDENTIFICATION
17  * src/backend/access/common/tupconvert.c
18  *
19  *-------------------------------------------------------------------------
20  */
21 #include "postgres.h"
22 
23 #include "access/htup_details.h"
24 #include "access/tupconvert.h"
25 #include "utils/builtins.h"
26 
27 
28 /*
29  * The conversion setup routines have the following common API:
30  *
31  * The setup routine checks whether the given source and destination tuple
32  * descriptors are logically compatible. If not, it throws an error.
33  * If so, it returns NULL if they are physically compatible (ie, no conversion
34  * is needed), else a TupleConversionMap that can be used by do_convert_tuple
35  * to perform the conversion.
36  *
37  * The TupleConversionMap, if needed, is palloc'd in the caller's memory
38  * context. Also, the given tuple descriptors are referenced by the map,
39  * so they must survive as long as the map is needed.
40  *
41  * The caller must supply a suitable primary error message to be used if
42  * a compatibility error is thrown. Recommended coding practice is to use
43  * gettext_noop() on this string, so that it is translatable but won't
44  * actually be translated unless the error gets thrown.
45  *
46  *
47  * Implementation notes:
48  *
49  * The key component of a TupleConversionMap is an attrMap[] array with
50  * one entry per output column. This entry contains the 1-based index of
51  * the corresponding input column, or zero to force a NULL value (for
52  * a dropped output column). The TupleConversionMap also contains workspace
53  * arrays.
54  */
55 
56 
57 /*
58  * Set up for tuple conversion, matching input and output columns by
59  * position. (Dropped columns are ignored in both input and output.)
60  *
61  * Note: the errdetail messages speak of indesc as the "returned" rowtype,
62  * outdesc as the "expected" rowtype. This is okay for current uses but
63  * might need generalization in future.
64  */
67  TupleDesc outdesc,
68  const char *msg)
69 {
70  TupleConversionMap *map;
71  AttrNumber *attrMap;
72  int nincols;
73  int noutcols;
74  int n;
75  int i;
76  int j;
77  bool same;
78 
79  /* Verify compatibility and prepare attribute-number map */
80  n = outdesc->natts;
81  attrMap = (AttrNumber *) palloc0(n * sizeof(AttrNumber));
82  j = 0; /* j is next physical input attribute */
83  nincols = noutcols = 0; /* these count non-dropped attributes */
84  same = true;
85  for (i = 0; i < n; i++)
86  {
87  Form_pg_attribute att = outdesc->attrs[i];
88  Oid atttypid;
89  int32 atttypmod;
90 
91  if (att->attisdropped)
92  continue; /* attrMap[i] is already 0 */
93  noutcols++;
94  atttypid = att->atttypid;
95  atttypmod = att->atttypmod;
96  for (; j < indesc->natts; j++)
97  {
98  att = indesc->attrs[j];
99  if (att->attisdropped)
100  continue;
101  nincols++;
102  /* Found matching column, check type */
103  if (atttypid != att->atttypid ||
104  (atttypmod != att->atttypmod && atttypmod >= 0))
105  ereport(ERROR,
106  (errcode(ERRCODE_DATATYPE_MISMATCH),
107  errmsg_internal("%s", _(msg)),
108  errdetail("Returned type %s does not match expected type %s in column %d.",
109  format_type_with_typemod(att->atttypid,
110  att->atttypmod),
111  format_type_with_typemod(atttypid,
112  atttypmod),
113  noutcols)));
114  attrMap[i] = (AttrNumber) (j + 1);
115  j++;
116  break;
117  }
118  if (attrMap[i] == 0)
119  same = false; /* we'll complain below */
120  }
121 
122  /* Check for unused input columns */
123  for (; j < indesc->natts; j++)
124  {
125  if (indesc->attrs[j]->attisdropped)
126  continue;
127  nincols++;
128  same = false; /* we'll complain below */
129  }
130 
131  /* Report column count mismatch using the non-dropped-column counts */
132  if (!same)
133  ereport(ERROR,
134  (errcode(ERRCODE_DATATYPE_MISMATCH),
135  errmsg_internal("%s", _(msg)),
136  errdetail("Number of returned columns (%d) does not match "
137  "expected column count (%d).",
138  nincols, noutcols)));
139 
140  /*
141  * Check to see if the map is one-to-one, in which case we need not do
142  * the tuple conversion. That's not enough though if either source or
143  * destination (tuples) contains OIDs; we'd need conversion in that case
144  * to inject the right OID into the tuple datum.
145  */
146  if (indesc->natts == outdesc->natts &&
147  !indesc->tdhasoid && !outdesc->tdhasoid)
148  {
149  for (i = 0; i < n; i++)
150  {
151  if (attrMap[i] == (i + 1))
152  continue;
153 
154  /*
155  * If it's a dropped column and the corresponding input column is
156  * also dropped, we needn't convert. However, attlen and attalign
157  * must agree.
158  */
159  if (attrMap[i] == 0 &&
160  indesc->attrs[i]->attisdropped &&
161  indesc->attrs[i]->attlen == outdesc->attrs[i]->attlen &&
162  indesc->attrs[i]->attalign == outdesc->attrs[i]->attalign)
163  continue;
164 
165  same = false;
166  break;
167  }
168  }
169  else
170  same = false;
171 
172  if (same)
173  {
174  /* Runtime conversion is not needed */
175  pfree(attrMap);
176  return NULL;
177  }
178 
179  /* Prepare the map structure */
180  map = (TupleConversionMap *) palloc(sizeof(TupleConversionMap));
181  map->indesc = indesc;
182  map->outdesc = outdesc;
183  map->attrMap = attrMap;
184  /* preallocate workspace for Datum arrays */
185  map->outvalues = (Datum *) palloc(n * sizeof(Datum));
186  map->outisnull = (bool *) palloc(n * sizeof(bool));
187  n = indesc->natts + 1; /* +1 for NULL */
188  map->invalues = (Datum *) palloc(n * sizeof(Datum));
189  map->inisnull = (bool *) palloc(n * sizeof(bool));
190  map->invalues[0] = (Datum) 0; /* set up the NULL entry */
191  map->inisnull[0] = true;
192 
193  return map;
194 }
195 
196 /*
197  * Set up for tuple conversion, matching input and output columns by name.
198  * (Dropped columns are ignored in both input and output.) This is intended
199  * for use when the rowtypes are related by inheritance, so we expect an exact
200  * match of both type and typmod. The error messages will be a bit unhelpful
201  * unless both rowtypes are named composite types.
202  */
205  TupleDesc outdesc,
206  const char *msg)
207 {
208  TupleConversionMap *map;
209  AttrNumber *attrMap;
210  int n = outdesc->natts;
211  int i;
212  bool same;
213 
214  /* Verify compatibility and prepare attribute-number map */
215  attrMap = convert_tuples_by_name_map(indesc, outdesc, msg);
216 
217  /*
218  * Check to see if the map is one-to-one, in which case we need not do
219  * the tuple conversion. That's not enough though if either source or
220  * destination (tuples) contains OIDs; we'd need conversion in that case
221  * to inject the right OID into the tuple datum.
222  */
223  if (indesc->natts == outdesc->natts &&
224  !indesc->tdhasoid && !outdesc->tdhasoid)
225  {
226  same = true;
227  for (i = 0; i < n; i++)
228  {
229  if (attrMap[i] == (i + 1))
230  continue;
231 
232  /*
233  * If it's a dropped column and the corresponding input column is
234  * also dropped, we needn't convert. However, attlen and attalign
235  * must agree.
236  */
237  if (attrMap[i] == 0 &&
238  indesc->attrs[i]->attisdropped &&
239  indesc->attrs[i]->attlen == outdesc->attrs[i]->attlen &&
240  indesc->attrs[i]->attalign == outdesc->attrs[i]->attalign)
241  continue;
242 
243  same = false;
244  break;
245  }
246  }
247  else
248  same = false;
249 
250  if (same)
251  {
252  /* Runtime conversion is not needed */
253  pfree(attrMap);
254  return NULL;
255  }
256 
257  /* Prepare the map structure */
258  map = (TupleConversionMap *) palloc(sizeof(TupleConversionMap));
259  map->indesc = indesc;
260  map->outdesc = outdesc;
261  map->attrMap = attrMap;
262  /* preallocate workspace for Datum arrays */
263  map->outvalues = (Datum *) palloc(n * sizeof(Datum));
264  map->outisnull = (bool *) palloc(n * sizeof(bool));
265  n = indesc->natts + 1; /* +1 for NULL */
266  map->invalues = (Datum *) palloc(n * sizeof(Datum));
267  map->inisnull = (bool *) palloc(n * sizeof(bool));
268  map->invalues[0] = (Datum) 0; /* set up the NULL entry */
269  map->inisnull[0] = true;
270 
271  return map;
272 }
273 
274 /*
275  * Return a palloc'd bare attribute map for tuple conversion, matching input
276  * and output columns by name. (Dropped columns are ignored in both input and
277  * output.) This is normally a subroutine for convert_tuples_by_name, but can
278  * be used standalone.
279  */
280 AttrNumber *
282  TupleDesc outdesc,
283  const char *msg)
284 {
285  AttrNumber *attrMap;
286  int n;
287  int i;
288 
289  n = outdesc->natts;
290  attrMap = (AttrNumber *) palloc0(n * sizeof(AttrNumber));
291  for (i = 0; i < n; i++)
292  {
293  Form_pg_attribute att = outdesc->attrs[i];
294  char *attname;
295  Oid atttypid;
296  int32 atttypmod;
297  int j;
298 
299  if (att->attisdropped)
300  continue; /* attrMap[i] is already 0 */
301  attname = NameStr(att->attname);
302  atttypid = att->atttypid;
303  atttypmod = att->atttypmod;
304  for (j = 0; j < indesc->natts; j++)
305  {
306  att = indesc->attrs[j];
307  if (att->attisdropped)
308  continue;
309  if (strcmp(attname, NameStr(att->attname)) == 0)
310  {
311  /* Found it, check type */
312  if (atttypid != att->atttypid || atttypmod != att->atttypmod)
313  ereport(ERROR,
314  (errcode(ERRCODE_DATATYPE_MISMATCH),
315  errmsg_internal("%s", _(msg)),
316  errdetail("Attribute \"%s\" of type %s does not match corresponding attribute of type %s.",
317  attname,
318  format_type_be(outdesc->tdtypeid),
319  format_type_be(indesc->tdtypeid))));
320  attrMap[i] = (AttrNumber) (j + 1);
321  break;
322  }
323  }
324  if (attrMap[i] == 0)
325  ereport(ERROR,
326  (errcode(ERRCODE_DATATYPE_MISMATCH),
327  errmsg_internal("%s", _(msg)),
328  errdetail("Attribute \"%s\" of type %s does not exist in type %s.",
329  attname,
330  format_type_be(outdesc->tdtypeid),
331  format_type_be(indesc->tdtypeid))));
332  }
333 
334  return attrMap;
335 }
336 
337 /*
338  * Perform conversion of a tuple according to the map.
339  */
340 HeapTuple
342 {
343  AttrNumber *attrMap = map->attrMap;
344  Datum *invalues = map->invalues;
345  bool *inisnull = map->inisnull;
346  Datum *outvalues = map->outvalues;
347  bool *outisnull = map->outisnull;
348  int outnatts = map->outdesc->natts;
349  int i;
350 
351  /*
352  * Extract all the values of the old tuple, offsetting the arrays so that
353  * invalues[0] is left NULL and invalues[1] is the first source attribute;
354  * this exactly matches the numbering convention in attrMap.
355  */
356  heap_deform_tuple(tuple, map->indesc, invalues + 1, inisnull + 1);
357 
358  /*
359  * Transpose into proper fields of the new tuple.
360  */
361  for (i = 0; i < outnatts; i++)
362  {
363  int j = attrMap[i];
364 
365  outvalues[i] = invalues[j];
366  outisnull[i] = inisnull[j];
367  }
368 
369  /*
370  * Now form the new tuple.
371  */
372  return heap_form_tuple(map->outdesc, outvalues, outisnull);
373 }
374 
375 /*
376  * Free a TupleConversionMap structure.
377  */
378 void
380 {
381  /* indesc and outdesc are not ours to free */
382  pfree(map->attrMap);
383  pfree(map->invalues);
384  pfree(map->inisnull);
385  pfree(map->outvalues);
386  pfree(map->outisnull);
387  pfree(map);
388 }
AttrNumber * attrMap
Definition: tupconvert.h:25
TupleDesc indesc
Definition: tupconvert.h:23
Oid tdtypeid
Definition: tupdesc.h:77
TupleDesc outdesc
Definition: tupconvert.h:24
bool tdhasoid
Definition: tupdesc.h:79
TupleConversionMap * convert_tuples_by_position(TupleDesc indesc, TupleDesc outdesc, const char *msg)
Definition: tupconvert.c:66
Form_pg_attribute * attrs
Definition: tupdesc.h:74
int errcode(int sqlerrcode)
Definition: elog.c:575
char * format_type_be(Oid type_oid)
Definition: format_type.c:94
HeapTuple heap_form_tuple(TupleDesc tupleDescriptor, Datum *values, bool *isnull)
Definition: heaptuple.c:692
unsigned int Oid
Definition: postgres_ext.h:31
int natts
Definition: tupdesc.h:73
signed int int32
Definition: c.h:253
void pfree(void *pointer)
Definition: mcxt.c:992
#define ERROR
Definition: elog.h:43
int errdetail(const char *fmt,...)
Definition: elog.c:873
void free_conversion_map(TupleConversionMap *map)
Definition: tupconvert.c:379
FormData_pg_attribute * Form_pg_attribute
Definition: pg_attribute.h:184
#define ereport(elevel, rest)
Definition: elog.h:122
TupleConversionMap * convert_tuples_by_name(TupleDesc indesc, TupleDesc outdesc, const char *msg)
Definition: tupconvert.c:204
AttrNumber * convert_tuples_by_name_map(TupleDesc indesc, TupleDesc outdesc, const char *msg)
Definition: tupconvert.c:281
char * format_type_with_typemod(Oid type_oid, int32 typemod)
Definition: format_type.c:113
void * palloc0(Size size)
Definition: mcxt.c:920
uintptr_t Datum
Definition: postgres.h:374
int errmsg_internal(const char *fmt,...)
Definition: elog.c:827
#define NULL
Definition: c.h:226
HeapTuple do_convert_tuple(HeapTuple tuple, TupleConversionMap *map)
Definition: tupconvert.c:341
void heap_deform_tuple(HeapTuple tuple, TupleDesc tupleDesc, Datum *values, bool *isnull)
Definition: heaptuple.c:935
void * palloc(Size size)
Definition: mcxt.c:891
int i
#define NameStr(name)
Definition: c.h:495
int16 AttrNumber
Definition: attnum.h:21
#define _(x)
Definition: elog.c:84