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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 of 8 : * dropped columns. 9 : * 10 : * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group 11 : * Portions Copyright (c) 1994, Regents of the University of California 12 : * 13 : * 14 : * IDENTIFICATION 15 : * src/backend/access/common/tupconvert.c 16 : * 17 : *------------------------------------------------------------------------- 18 : */ 19 : #include "postgres.h" 20 : 21 : #include "access/htup_details.h" 22 : #include "access/tupconvert.h" 23 : #include "executor/tuptable.h" 24 : 25 : 26 : /* 27 : * The conversion setup routines have the following common API: 28 : * 29 : * The setup routine checks using attmap.c whether the given source and 30 : * destination tuple descriptors are logically compatible. If not, it throws 31 : * an error. If so, it returns NULL if they are physically compatible (ie, no 32 : * conversion is needed), else a TupleConversionMap that can be used by 33 : * execute_attr_map_tuple or execute_attr_map_slot to perform the conversion. 34 : * 35 : * The TupleConversionMap, if needed, is palloc'd in the caller's memory 36 : * context. Also, the given tuple descriptors are referenced by the map, 37 : * so they must survive as long as the map is needed. 38 : * 39 : * The caller must supply a suitable primary error message to be used if 40 : * a compatibility error is thrown. Recommended coding practice is to use 41 : * gettext_noop() on this string, so that it is translatable but won't 42 : * actually be translated unless the error gets thrown. 43 : * 44 : * 45 : * Implementation notes: 46 : * 47 : * The key component of a TupleConversionMap is an attrMap[] array with 48 : * one entry per output column. This entry contains the 1-based index of 49 : * the corresponding input column, or zero to force a NULL value (for 50 : * a dropped output column). The TupleConversionMap also contains workspace 51 : * arrays. 52 : */ 53 : 54 : 55 : /* 56 : * Set up for tuple conversion, matching input and output columns by 57 : * position. (Dropped columns are ignored in both input and output.) 58 : */ 59 : TupleConversionMap * 60 9624 : convert_tuples_by_position(TupleDesc indesc, 61 : TupleDesc outdesc, 62 : const char *msg) 63 : { 64 : TupleConversionMap *map; 65 : int n; 66 : AttrMap *attrMap; 67 : 68 : /* Verify compatibility and prepare attribute-number map */ 69 9624 : attrMap = build_attrmap_by_position(indesc, outdesc, msg); 70 : 71 9590 : if (attrMap == NULL) 72 : { 73 : /* runtime conversion is not needed */ 74 9494 : return NULL; 75 : } 76 : 77 : /* Prepare the map structure */ 78 96 : map = (TupleConversionMap *) palloc(sizeof(TupleConversionMap)); 79 96 : map->indesc = indesc; 80 96 : map->outdesc = outdesc; 81 96 : map->attrMap = attrMap; 82 : /* preallocate workspace for Datum arrays */ 83 96 : n = outdesc->natts + 1; /* +1 for NULL */ 84 96 : map->outvalues = (Datum *) palloc(n * sizeof(Datum)); 85 96 : map->outisnull = (bool *) palloc(n * sizeof(bool)); 86 96 : n = indesc->natts + 1; /* +1 for NULL */ 87 96 : map->invalues = (Datum *) palloc(n * sizeof(Datum)); 88 96 : map->inisnull = (bool *) palloc(n * sizeof(bool)); 89 96 : map->invalues[0] = (Datum) 0; /* set up the NULL entry */ 90 96 : map->inisnull[0] = true; 91 : 92 96 : return map; 93 : } 94 : 95 : /* 96 : * Set up for tuple conversion, matching input and output columns by name. 97 : * (Dropped columns are ignored in both input and output.) This is intended 98 : * for use when the rowtypes are related by inheritance, so we expect an exact 99 : * match of both type and typmod. The error messages will be a bit unhelpful 100 : * unless both rowtypes are named composite types. 101 : */ 102 : TupleConversionMap * 103 3774 : convert_tuples_by_name(TupleDesc indesc, 104 : TupleDesc outdesc) 105 : { 106 : AttrMap *attrMap; 107 : 108 : /* Verify compatibility and prepare attribute-number map */ 109 3774 : attrMap = build_attrmap_by_name_if_req(indesc, outdesc, false); 110 : 111 3774 : if (attrMap == NULL) 112 : { 113 : /* runtime conversion is not needed */ 114 2954 : return NULL; 115 : } 116 : 117 820 : return convert_tuples_by_name_attrmap(indesc, outdesc, attrMap); 118 : } 119 : 120 : /* 121 : * Set up tuple conversion for input and output TupleDescs using the given 122 : * AttrMap. 123 : */ 124 : TupleConversionMap * 125 2296 : convert_tuples_by_name_attrmap(TupleDesc indesc, 126 : TupleDesc outdesc, 127 : AttrMap *attrMap) 128 : { 129 2296 : int n = outdesc->natts; 130 : TupleConversionMap *map; 131 : 132 : Assert(attrMap != NULL); 133 : 134 : /* Prepare the map structure */ 135 2296 : map = (TupleConversionMap *) palloc(sizeof(TupleConversionMap)); 136 2296 : map->indesc = indesc; 137 2296 : map->outdesc = outdesc; 138 2296 : map->attrMap = attrMap; 139 : /* preallocate workspace for Datum arrays */ 140 2296 : map->outvalues = (Datum *) palloc(n * sizeof(Datum)); 141 2296 : map->outisnull = (bool *) palloc(n * sizeof(bool)); 142 2296 : n = indesc->natts + 1; /* +1 for NULL */ 143 2296 : map->invalues = (Datum *) palloc(n * sizeof(Datum)); 144 2296 : map->inisnull = (bool *) palloc(n * sizeof(bool)); 145 2296 : map->invalues[0] = (Datum) 0; /* set up the NULL entry */ 146 2296 : map->inisnull[0] = true; 147 : 148 2296 : return map; 149 : } 150 : 151 : /* 152 : * Perform conversion of a tuple according to the map. 153 : */ 154 : HeapTuple 155 107106 : execute_attr_map_tuple(HeapTuple tuple, TupleConversionMap *map) 156 : { 157 107106 : AttrMap *attrMap = map->attrMap; 158 107106 : Datum *invalues = map->invalues; 159 107106 : bool *inisnull = map->inisnull; 160 107106 : Datum *outvalues = map->outvalues; 161 107106 : bool *outisnull = map->outisnull; 162 : int i; 163 : 164 : /* 165 : * Extract all the values of the old tuple, offsetting the arrays so that 166 : * invalues[0] is left NULL and invalues[1] is the first source attribute; 167 : * this exactly matches the numbering convention in attrMap. 168 : */ 169 107106 : heap_deform_tuple(tuple, map->indesc, invalues + 1, inisnull + 1); 170 : 171 : /* 172 : * Transpose into proper fields of the new tuple. 173 : */ 174 : Assert(attrMap->maplen == map->outdesc->natts); 175 426482 : for (i = 0; i < attrMap->maplen; i++) 176 : { 177 319376 : int j = attrMap->attnums[i]; 178 : 179 319376 : outvalues[i] = invalues[j]; 180 319376 : outisnull[i] = inisnull[j]; 181 : } 182 : 183 : /* 184 : * Now form the new tuple. 185 : */ 186 107106 : return heap_form_tuple(map->outdesc, outvalues, outisnull); 187 : } 188 : 189 : /* 190 : * Perform conversion of a tuple slot according to the map. 191 : */ 192 : TupleTableSlot * 193 143732 : execute_attr_map_slot(AttrMap *attrMap, 194 : TupleTableSlot *in_slot, 195 : TupleTableSlot *out_slot) 196 : { 197 : Datum *invalues; 198 : bool *inisnull; 199 : Datum *outvalues; 200 : bool *outisnull; 201 : int outnatts; 202 : int i; 203 : 204 : /* Sanity checks */ 205 : Assert(in_slot->tts_tupleDescriptor != NULL && 206 : out_slot->tts_tupleDescriptor != NULL); 207 : Assert(in_slot->tts_values != NULL && out_slot->tts_values != NULL); 208 : 209 143732 : outnatts = out_slot->tts_tupleDescriptor->natts; 210 : 211 : /* Extract all the values of the in slot. */ 212 143732 : slot_getallattrs(in_slot); 213 : 214 : /* Before doing the mapping, clear any old contents from the out slot */ 215 143732 : ExecClearTuple(out_slot); 216 : 217 143732 : invalues = in_slot->tts_values; 218 143732 : inisnull = in_slot->tts_isnull; 219 143732 : outvalues = out_slot->tts_values; 220 143732 : outisnull = out_slot->tts_isnull; 221 : 222 : /* Transpose into proper fields of the out slot. */ 223 579638 : for (i = 0; i < outnatts; i++) 224 : { 225 435906 : int j = attrMap->attnums[i] - 1; 226 : 227 : /* attrMap->attnums[i] == 0 means it's a NULL datum. */ 228 435906 : if (j == -1) 229 : { 230 2602 : outvalues[i] = (Datum) 0; 231 2602 : outisnull[i] = true; 232 : } 233 : else 234 : { 235 433304 : outvalues[i] = invalues[j]; 236 433304 : outisnull[i] = inisnull[j]; 237 : } 238 : } 239 : 240 143732 : ExecStoreVirtualTuple(out_slot); 241 : 242 143732 : return out_slot; 243 : } 244 : 245 : /* 246 : * Perform conversion of bitmap of columns according to the map. 247 : * 248 : * The input and output bitmaps are offset by 249 : * FirstLowInvalidHeapAttributeNumber to accommodate system cols, like the 250 : * column-bitmaps in RangeTblEntry. 251 : */ 252 : Bitmapset * 253 494 : execute_attr_map_cols(AttrMap *attrMap, Bitmapset *in_cols) 254 : { 255 : Bitmapset *out_cols; 256 : int out_attnum; 257 : 258 : /* fast path for the common trivial case */ 259 494 : if (in_cols == NULL) 260 4 : return NULL; 261 : 262 : /* 263 : * For each output column, check which input column it corresponds to. 264 : */ 265 490 : out_cols = NULL; 266 : 267 490 : for (out_attnum = FirstLowInvalidHeapAttributeNumber; 268 6248 : out_attnum <= attrMap->maplen; 269 5758 : out_attnum++) 270 : { 271 : int in_attnum; 272 : 273 5758 : if (out_attnum < 0) 274 : { 275 : /* System column. No mapping. */ 276 3430 : in_attnum = out_attnum; 277 : } 278 2328 : else if (out_attnum == 0) 279 490 : continue; 280 : else 281 : { 282 : /* normal user column */ 283 1838 : in_attnum = attrMap->attnums[out_attnum - 1]; 284 : 285 1838 : if (in_attnum == 0) 286 142 : continue; 287 : } 288 : 289 5126 : if (bms_is_member(in_attnum - FirstLowInvalidHeapAttributeNumber, in_cols)) 290 532 : out_cols = bms_add_member(out_cols, out_attnum - FirstLowInvalidHeapAttributeNumber); 291 : } 292 : 293 490 : return out_cols; 294 : } 295 : 296 : /* 297 : * Free a TupleConversionMap structure. 298 : */ 299 : void 300 170 : free_conversion_map(TupleConversionMap *map) 301 : { 302 : /* indesc and outdesc are not ours to free */ 303 170 : free_attrmap(map->attrMap); 304 170 : pfree(map->invalues); 305 170 : pfree(map->inisnull); 306 170 : pfree(map->outvalues); 307 170 : pfree(map->outisnull); 308 170 : pfree(map); 309 170 : }