Age Owner TLA Line data Source code
1 : /*-------------------------------------------------------------------------
2 : *
3 : * toast_helper.c
4 : * Helper functions for table AMs implementing compressed or
5 : * out-of-line storage of varlena attributes.
6 : *
7 : * Copyright (c) 2000-2023, PostgreSQL Global Development Group
8 : *
9 : * IDENTIFICATION
10 : * src/backend/access/table/toast_helper.c
11 : *
12 : *-------------------------------------------------------------------------
13 : */
14 :
15 : #include "postgres.h"
16 :
17 : #include "access/detoast.h"
18 : #include "access/table.h"
19 : #include "access/toast_helper.h"
20 : #include "access/toast_internals.h"
21 : #include "catalog/pg_type_d.h"
22 : #include "varatt.h"
23 :
24 :
25 : /*
26 : * Prepare to TOAST a tuple.
27 : *
28 : * tupleDesc, toast_values, and toast_isnull are required parameters; they
29 : * provide the necessary details about the tuple to be toasted.
30 : *
31 : * toast_oldvalues and toast_oldisnull should be NULL for a newly-inserted
32 : * tuple; for an update, they should describe the existing tuple.
33 : *
34 : * All of these arrays should have a length equal to tupleDesc->natts.
35 : *
36 : * On return, toast_flags and toast_attr will have been initialized.
37 : * toast_flags is just a single uint8, but toast_attr is a caller-provided
38 : * array with a length equal to tupleDesc->natts. The caller need not
39 : * perform any initialization of the array before calling this function.
40 : */
41 : void
1311 rhaas 42 GIC 63963 : toast_tuple_init(ToastTupleContext *ttc)
1311 rhaas 43 ECB : {
1311 rhaas 44 GIC 63963 : TupleDesc tupleDesc = ttc->ttc_rel->rd_att;
1311 rhaas 45 CBC 63963 : int numAttrs = tupleDesc->natts;
1311 rhaas 46 ECB : int i;
47 :
1311 rhaas 48 GIC 63963 : ttc->ttc_flags = 0;
1311 rhaas 49 ECB :
1311 rhaas 50 GIC 796506 : for (i = 0; i < numAttrs; i++)
1311 rhaas 51 ECB : {
1311 rhaas 52 GIC 732543 : Form_pg_attribute att = TupleDescAttr(tupleDesc, i);
1311 rhaas 53 ECB : struct varlena *old_value;
54 : struct varlena *new_value;
55 :
1311 rhaas 56 GIC 732543 : ttc->ttc_attr[i].tai_colflags = 0;
1311 rhaas 57 CBC 732543 : ttc->ttc_attr[i].tai_oldexternal = NULL;
751 58 732543 : ttc->ttc_attr[i].tai_compression = att->attcompression;
1311 rhaas 59 ECB :
1311 rhaas 60 GIC 732543 : if (ttc->ttc_oldvalues != NULL)
1311 rhaas 61 ECB : {
62 : /*
63 : * For UPDATE get the old and new values of this attribute
64 : */
65 : old_value =
1311 rhaas 66 GIC 87351 : (struct varlena *) DatumGetPointer(ttc->ttc_oldvalues[i]);
1311 rhaas 67 ECB : new_value =
1311 rhaas 68 GIC 87351 : (struct varlena *) DatumGetPointer(ttc->ttc_values[i]);
1311 rhaas 69 ECB :
70 : /*
71 : * If the old value is stored on disk, check if it has changed so
72 : * we have to delete it later.
73 : */
1311 rhaas 74 GIC 87351 : if (att->attlen == -1 && !ttc->ttc_oldisnull[i] &&
1311 rhaas 75 CBC 8838 : VARATT_IS_EXTERNAL_ONDISK(old_value))
1311 rhaas 76 ECB : {
1311 rhaas 77 GIC 261 : if (ttc->ttc_isnull[i] ||
1311 rhaas 78 CBC 252 : !VARATT_IS_EXTERNAL_ONDISK(new_value) ||
79 48 : memcmp((char *) old_value, (char *) new_value,
80 48 : VARSIZE_EXTERNAL(old_value)) != 0)
1311 rhaas 81 ECB : {
82 : /*
83 : * The old external stored value isn't needed any more
84 : * after the update
85 : */
1311 rhaas 86 GIC 214 : ttc->ttc_attr[i].tai_colflags |= TOASTCOL_NEEDS_DELETE_OLD;
1311 rhaas 87 CBC 214 : ttc->ttc_flags |= TOAST_NEEDS_DELETE_OLD;
1311 rhaas 88 ECB : }
89 : else
90 : {
91 : /*
92 : * This attribute isn't changed by this update so we reuse
93 : * the original reference to the old value in the new
94 : * tuple.
95 : */
1311 rhaas 96 GIC 47 : ttc->ttc_attr[i].tai_colflags |= TOASTCOL_IGNORE;
1311 rhaas 97 CBC 47 : continue;
1311 rhaas 98 ECB : }
99 : }
100 : }
101 : else
102 : {
103 : /*
104 : * For INSERT simply get the new value
105 : */
1311 rhaas 106 GIC 645192 : new_value = (struct varlena *) DatumGetPointer(ttc->ttc_values[i]);
1311 rhaas 107 ECB : }
108 :
109 : /*
110 : * Handle NULL attributes
111 : */
1311 rhaas 112 GIC 732496 : if (ttc->ttc_isnull[i])
1311 rhaas 113 ECB : {
1311 rhaas 114 GIC 75910 : ttc->ttc_attr[i].tai_colflags |= TOASTCOL_IGNORE;
1311 rhaas 115 CBC 75910 : ttc->ttc_flags |= TOAST_HAS_NULLS;
116 75910 : continue;
1311 rhaas 117 ECB : }
118 :
119 : /*
120 : * Now look at varlena attributes
121 : */
1311 rhaas 122 GIC 656586 : if (att->attlen == -1)
1311 rhaas 123 ECB : {
124 : /*
125 : * If the table's attribute says PLAIN always, force it so.
126 : */
1131 tgl 127 GIC 143621 : if (att->attstorage == TYPSTORAGE_PLAIN)
1311 rhaas 128 CBC 4902 : ttc->ttc_attr[i].tai_colflags |= TOASTCOL_IGNORE;
1311 rhaas 129 ECB :
130 : /*
131 : * We took care of UPDATE above, so any external value we find
132 : * still in the tuple must be someone else's that we cannot reuse
133 : * (this includes the case of an out-of-line in-memory datum).
134 : * Fetch it back (without decompression, unless we are forcing
135 : * PLAIN storage). If necessary, we'll push it out as a new
136 : * external value below.
137 : */
1311 rhaas 138 GIC 143621 : if (VARATT_IS_EXTERNAL(new_value))
1311 rhaas 139 ECB : {
1311 rhaas 140 GIC 472 : ttc->ttc_attr[i].tai_oldexternal = new_value;
1131 tgl 141 CBC 472 : if (att->attstorage == TYPSTORAGE_PLAIN)
1283 rhaas 142 LBC 0 : new_value = detoast_attr(new_value);
1311 rhaas 143 EUB : else
1283 rhaas 144 GIC 472 : new_value = detoast_external_attr(new_value);
1311 rhaas 145 CBC 472 : ttc->ttc_values[i] = PointerGetDatum(new_value);
146 472 : ttc->ttc_attr[i].tai_colflags |= TOASTCOL_NEEDS_FREE;
147 472 : ttc->ttc_flags |= (TOAST_NEEDS_CHANGE | TOAST_NEEDS_FREE);
1311 rhaas 148 ECB : }
149 :
150 : /*
151 : * Remember the size of this attribute
152 : */
1311 rhaas 153 GIC 143621 : ttc->ttc_attr[i].tai_size = VARSIZE_ANY(new_value);
1311 rhaas 154 ECB : }
155 : else
156 : {
157 : /*
158 : * Not a varlena attribute, plain storage always
159 : */
1311 rhaas 160 GIC 512965 : ttc->ttc_attr[i].tai_colflags |= TOASTCOL_IGNORE;
1311 rhaas 161 ECB : }
162 : }
1311 rhaas 163 GIC 63963 : }
1311 rhaas 164 ECB :
165 : /*
166 : * Find the largest varlena attribute that satisfies certain criteria.
167 : *
168 : * The relevant column must not be marked TOASTCOL_IGNORE, and if the
169 : * for_compression flag is passed as true, it must also not be marked
170 : * TOASTCOL_INCOMPRESSIBLE.
171 : *
172 : * The column must have attstorage EXTERNAL or EXTENDED if check_main is
173 : * false, and must have attstorage MAIN if check_main is true.
174 : *
175 : * The column must have a minimum size of MAXALIGN(TOAST_POINTER_SIZE);
176 : * if not, no benefit is to be expected by compressing it.
177 : *
178 : * The return value is the index of the biggest suitable column, or
179 : * -1 if there is none.
180 : */
181 : int
1311 rhaas 182 GIC 77710 : toast_tuple_find_biggest_attribute(ToastTupleContext *ttc,
1311 rhaas 183 ECB : bool for_compression, bool check_main)
184 : {
1311 rhaas 185 GIC 77710 : TupleDesc tupleDesc = ttc->ttc_rel->rd_att;
1311 rhaas 186 CBC 77710 : int numAttrs = tupleDesc->natts;
187 77710 : int biggest_attno = -1;
188 77710 : int32 biggest_size = MAXALIGN(TOAST_POINTER_SIZE);
189 77710 : int32 skip_colflags = TOASTCOL_IGNORE;
1311 rhaas 190 ECB : int i;
191 :
1311 rhaas 192 GIC 77710 : if (for_compression)
1311 rhaas 193 CBC 74679 : skip_colflags |= TOASTCOL_INCOMPRESSIBLE;
1311 rhaas 194 ECB :
1311 rhaas 195 GIC 1158953 : for (i = 0; i < numAttrs; i++)
1311 rhaas 196 ECB : {
1311 rhaas 197 GIC 1081243 : Form_pg_attribute att = TupleDescAttr(tupleDesc, i);
1311 rhaas 198 ECB :
1311 rhaas 199 GIC 1081243 : if ((ttc->ttc_attr[i].tai_colflags & skip_colflags) != 0)
1311 rhaas 200 CBC 893371 : continue;
201 187872 : if (VARATT_IS_EXTERNAL(DatumGetPointer(ttc->ttc_values[i])))
1131 tgl 202 LBC 0 : continue; /* can't happen, toast_action would be PLAIN */
1311 rhaas 203 GBC 187872 : if (for_compression &&
1311 rhaas 204 CBC 179483 : VARATT_IS_COMPRESSED(DatumGetPointer(ttc->ttc_values[i])))
205 15612 : continue;
1131 tgl 206 172260 : if (check_main && att->attstorage != TYPSTORAGE_MAIN)
1311 rhaas 207 LBC 0 : continue;
1131 tgl 208 GBC 172260 : if (!check_main && att->attstorage != TYPSTORAGE_EXTENDED &&
1131 tgl 209 CBC 2956 : att->attstorage != TYPSTORAGE_EXTERNAL)
1311 rhaas 210 56 : continue;
1311 rhaas 211 ECB :
1311 rhaas 212 GIC 172204 : if (ttc->ttc_attr[i].tai_size > biggest_size)
1311 rhaas 213 ECB : {
1311 rhaas 214 GIC 100285 : biggest_attno = i;
1311 rhaas 215 CBC 100285 : biggest_size = ttc->ttc_attr[i].tai_size;
1311 rhaas 216 ECB : }
217 : }
218 :
1311 rhaas 219 GIC 77710 : return biggest_attno;
1311 rhaas 220 ECB : }
221 :
222 : /*
223 : * Try compression for an attribute.
224 : *
225 : * If we find that the attribute is not compressible, mark it so.
226 : */
227 : void
1311 rhaas 228 GIC 68769 : toast_tuple_try_compression(ToastTupleContext *ttc, int attribute)
1311 rhaas 229 ECB : {
1311 rhaas 230 GIC 68769 : Datum *value = &ttc->ttc_values[attribute];
751 rhaas 231 ECB : Datum new_value;
1311 rhaas 232 GIC 68769 : ToastAttrInfo *attr = &ttc->ttc_attr[attribute];
1311 rhaas 233 ECB :
751 rhaas 234 GIC 68769 : new_value = toast_compress_datum(*value, attr->tai_compression);
751 rhaas 235 ECB :
1311 rhaas 236 GIC 68769 : if (DatumGetPointer(new_value) != NULL)
1311 rhaas 237 ECB : {
238 : /* successful compression */
1311 rhaas 239 GIC 67221 : if ((attr->tai_colflags & TOASTCOL_NEEDS_FREE) != 0)
1311 rhaas 240 CBC 61 : pfree(DatumGetPointer(*value));
241 67221 : *value = new_value;
242 67221 : attr->tai_colflags |= TOASTCOL_NEEDS_FREE;
243 67221 : attr->tai_size = VARSIZE(DatumGetPointer(*value));
244 67221 : ttc->ttc_flags |= (TOAST_NEEDS_CHANGE | TOAST_NEEDS_FREE);
1311 rhaas 245 ECB : }
246 : else
247 : {
248 : /* incompressible, ignore on subsequent compression passes */
1311 rhaas 249 GIC 1548 : attr->tai_colflags |= TOASTCOL_INCOMPRESSIBLE;
1311 rhaas 250 ECB : }
1311 rhaas 251 GIC 68769 : }
1311 rhaas 252 ECB :
253 : /*
254 : * Move an attribute to external storage.
255 : */
256 : void
1311 rhaas 257 GIC 32344 : toast_tuple_externalize(ToastTupleContext *ttc, int attribute, int options)
1311 rhaas 258 ECB : {
1311 rhaas 259 GIC 32344 : Datum *value = &ttc->ttc_values[attribute];
1311 rhaas 260 CBC 32344 : Datum old_value = *value;
261 32344 : ToastAttrInfo *attr = &ttc->ttc_attr[attribute];
1311 rhaas 262 ECB :
1311 rhaas 263 GIC 32344 : attr->tai_colflags |= TOASTCOL_IGNORE;
1311 rhaas 264 CBC 32344 : *value = toast_save_datum(ttc->ttc_rel, old_value, attr->tai_oldexternal,
1311 rhaas 265 ECB : options);
1311 rhaas 266 GIC 32344 : if ((attr->tai_colflags & TOASTCOL_NEEDS_FREE) != 0)
1311 rhaas 267 CBC 29430 : pfree(DatumGetPointer(old_value));
268 32344 : attr->tai_colflags |= TOASTCOL_NEEDS_FREE;
269 32344 : ttc->ttc_flags |= (TOAST_NEEDS_CHANGE | TOAST_NEEDS_FREE);
270 32344 : }
1311 rhaas 271 ECB :
272 : /*
273 : * Perform appropriate cleanup after one tuple has been subjected to TOAST.
274 : */
275 : void
1311 rhaas 276 GIC 63963 : toast_tuple_cleanup(ToastTupleContext *ttc)
1311 rhaas 277 ECB : {
1311 rhaas 278 GIC 63963 : TupleDesc tupleDesc = ttc->ttc_rel->rd_att;
1311 rhaas 279 CBC 63963 : int numAttrs = tupleDesc->natts;
1311 rhaas 280 ECB :
281 : /*
282 : * Free allocated temp values
283 : */
1311 rhaas 284 GIC 63963 : if ((ttc->ttc_flags & TOAST_NEEDS_FREE) != 0)
1311 rhaas 285 ECB : {
286 : int i;
287 :
1311 rhaas 288 GIC 795670 : for (i = 0; i < numAttrs; i++)
1311 rhaas 289 ECB : {
1311 rhaas 290 GIC 731772 : ToastAttrInfo *attr = &ttc->ttc_attr[i];
1311 rhaas 291 ECB :
1311 rhaas 292 GIC 731772 : if ((attr->tai_colflags & TOASTCOL_NEEDS_FREE) != 0)
1311 rhaas 293 CBC 70546 : pfree(DatumGetPointer(ttc->ttc_values[i]));
1311 rhaas 294 ECB : }
295 : }
296 :
297 : /*
298 : * Delete external values from the old tuple
299 : */
1311 rhaas 300 GIC 63963 : if ((ttc->ttc_flags & TOAST_NEEDS_DELETE_OLD) != 0)
1311 rhaas 301 ECB : {
302 : int i;
303 :
1311 rhaas 304 GIC 4506 : for (i = 0; i < numAttrs; i++)
1311 rhaas 305 ECB : {
1311 rhaas 306 GIC 4321 : ToastAttrInfo *attr = &ttc->ttc_attr[i];
1311 rhaas 307 ECB :
1311 rhaas 308 GIC 4321 : if ((attr->tai_colflags & TOASTCOL_NEEDS_DELETE_OLD) != 0)
1311 rhaas 309 CBC 214 : toast_delete_datum(ttc->ttc_rel, ttc->ttc_oldvalues[i], false);
1311 rhaas 310 ECB : }
311 : }
1311 rhaas 312 GIC 63963 : }
1311 rhaas 313 ECB :
314 : /*
315 : * Check for external stored attributes and delete them from the secondary
316 : * relation.
317 : */
318 : void
1311 rhaas 319 GIC 234 : toast_delete_external(Relation rel, Datum *values, bool *isnull,
1311 rhaas 320 ECB : bool is_speculative)
321 : {
1311 rhaas 322 GIC 234 : TupleDesc tupleDesc = rel->rd_att;
1311 rhaas 323 CBC 234 : int numAttrs = tupleDesc->natts;
1311 rhaas 324 ECB : int i;
325 :
1311 rhaas 326 GIC 1540 : for (i = 0; i < numAttrs; i++)
1311 rhaas 327 ECB : {
1311 rhaas 328 GIC 1306 : if (TupleDescAttr(tupleDesc, i)->attlen == -1)
1311 rhaas 329 ECB : {
1311 rhaas 330 GIC 472 : Datum value = values[i];
1311 rhaas 331 ECB :
1311 rhaas 332 GIC 472 : if (isnull[i])
1311 rhaas 333 CBC 126 : continue;
224 peter 334 GNC 346 : else if (VARATT_IS_EXTERNAL_ONDISK(value))
1311 rhaas 335 CBC 244 : toast_delete_datum(rel, value, is_speculative);
1311 rhaas 336 ECB : }
337 : }
1311 rhaas 338 GIC 234 : }
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