Line data Source code
1 : /*-------------------------------------------------------------------------
2 : *
3 : * file_fdw.c
4 : * foreign-data wrapper for server-side flat files (or programs).
5 : *
6 : * Copyright (c) 2010-2023, PostgreSQL Global Development Group
7 : *
8 : * IDENTIFICATION
9 : * contrib/file_fdw/file_fdw.c
10 : *
11 : *-------------------------------------------------------------------------
12 : */
13 : #include "postgres.h"
14 :
15 : #include <sys/stat.h>
16 : #include <unistd.h>
17 :
18 : #include "access/htup_details.h"
19 : #include "access/reloptions.h"
20 : #include "access/sysattr.h"
21 : #include "access/table.h"
22 : #include "catalog/pg_authid.h"
23 : #include "catalog/pg_foreign_table.h"
24 : #include "commands/copy.h"
25 : #include "commands/defrem.h"
26 : #include "commands/explain.h"
27 : #include "commands/vacuum.h"
28 : #include "foreign/fdwapi.h"
29 : #include "foreign/foreign.h"
30 : #include "miscadmin.h"
31 : #include "nodes/makefuncs.h"
32 : #include "optimizer/optimizer.h"
33 : #include "optimizer/pathnode.h"
34 : #include "optimizer/planmain.h"
35 : #include "optimizer/restrictinfo.h"
36 : #include "utils/acl.h"
37 : #include "utils/memutils.h"
38 : #include "utils/rel.h"
39 : #include "utils/sampling.h"
40 : #include "utils/varlena.h"
41 :
42 2 : PG_MODULE_MAGIC;
43 :
44 : /*
45 : * Describes the valid options for objects that use this wrapper.
46 : */
47 : struct FileFdwOption
48 : {
49 : const char *optname;
50 : Oid optcontext; /* Oid of catalog in which option may appear */
51 : };
52 :
53 : /*
54 : * Valid options for file_fdw.
55 : * These options are based on the options for the COPY FROM command.
56 : * But note that force_not_null and force_null are handled as boolean options
57 : * attached to a column, not as table options.
58 : *
59 : * Note: If you are adding new option for user mapping, you need to modify
60 : * fileGetOptions(), which currently doesn't bother to look at user mappings.
61 : */
62 : static const struct FileFdwOption valid_options[] = {
63 : /* Data source options */
64 : {"filename", ForeignTableRelationId},
65 : {"program", ForeignTableRelationId},
66 :
67 : /* Format options */
68 : /* oids option is not supported */
69 : {"format", ForeignTableRelationId},
70 : {"header", ForeignTableRelationId},
71 : {"delimiter", ForeignTableRelationId},
72 : {"quote", ForeignTableRelationId},
73 : {"escape", ForeignTableRelationId},
74 : {"null", ForeignTableRelationId},
75 : {"default", ForeignTableRelationId},
76 : {"encoding", ForeignTableRelationId},
77 : {"force_not_null", AttributeRelationId},
78 : {"force_null", AttributeRelationId},
79 :
80 : /*
81 : * force_quote is not supported by file_fdw because it's for COPY TO.
82 : */
83 :
84 : /* Sentinel */
85 : {NULL, InvalidOid}
86 : };
87 :
88 : /*
89 : * FDW-specific information for RelOptInfo.fdw_private.
90 : */
91 : typedef struct FileFdwPlanState
92 : {
93 : char *filename; /* file or program to read from */
94 : bool is_program; /* true if filename represents an OS command */
95 : List *options; /* merged COPY options, excluding filename and
96 : * is_program */
97 : BlockNumber pages; /* estimate of file's physical size */
98 : double ntuples; /* estimate of number of data rows */
99 : } FileFdwPlanState;
100 :
101 : /*
102 : * FDW-specific information for ForeignScanState.fdw_state.
103 : */
104 : typedef struct FileFdwExecutionState
105 : {
106 : char *filename; /* file or program to read from */
107 : bool is_program; /* true if filename represents an OS command */
108 : List *options; /* merged COPY options, excluding filename and
109 : * is_program */
110 : CopyFromState cstate; /* COPY execution state */
111 : } FileFdwExecutionState;
112 :
113 : /*
114 : * SQL functions
115 : */
116 4 : PG_FUNCTION_INFO_V1(file_fdw_handler);
117 4 : PG_FUNCTION_INFO_V1(file_fdw_validator);
118 :
119 : /*
120 : * FDW callback routines
121 : */
122 : static void fileGetForeignRelSize(PlannerInfo *root,
123 : RelOptInfo *baserel,
124 : Oid foreigntableid);
125 : static void fileGetForeignPaths(PlannerInfo *root,
126 : RelOptInfo *baserel,
127 : Oid foreigntableid);
128 : static ForeignScan *fileGetForeignPlan(PlannerInfo *root,
129 : RelOptInfo *baserel,
130 : Oid foreigntableid,
131 : ForeignPath *best_path,
132 : List *tlist,
133 : List *scan_clauses,
134 : Plan *outer_plan);
135 : static void fileExplainForeignScan(ForeignScanState *node, ExplainState *es);
136 : static void fileBeginForeignScan(ForeignScanState *node, int eflags);
137 : static TupleTableSlot *fileIterateForeignScan(ForeignScanState *node);
138 : static void fileReScanForeignScan(ForeignScanState *node);
139 : static void fileEndForeignScan(ForeignScanState *node);
140 : static bool fileAnalyzeForeignTable(Relation relation,
141 : AcquireSampleRowsFunc *func,
142 : BlockNumber *totalpages);
143 : static bool fileIsForeignScanParallelSafe(PlannerInfo *root, RelOptInfo *rel,
144 : RangeTblEntry *rte);
145 :
146 : /*
147 : * Helper functions
148 : */
149 : static bool is_valid_option(const char *option, Oid context);
150 : static void fileGetOptions(Oid foreigntableid,
151 : char **filename,
152 : bool *is_program,
153 : List **other_options);
154 : static List *get_file_fdw_attribute_options(Oid relid);
155 : static bool check_selective_binary_conversion(RelOptInfo *baserel,
156 : Oid foreigntableid,
157 : List **columns);
158 : static void estimate_size(PlannerInfo *root, RelOptInfo *baserel,
159 : FileFdwPlanState *fdw_private);
160 : static void estimate_costs(PlannerInfo *root, RelOptInfo *baserel,
161 : FileFdwPlanState *fdw_private,
162 : Cost *startup_cost, Cost *total_cost);
163 : static int file_acquire_sample_rows(Relation onerel, int elevel,
164 : HeapTuple *rows, int targrows,
165 : double *totalrows, double *totaldeadrows);
166 :
167 :
168 : /*
169 : * Foreign-data wrapper handler function: return a struct with pointers
170 : * to my callback routines.
171 : */
172 : Datum
173 30 : file_fdw_handler(PG_FUNCTION_ARGS)
174 : {
175 30 : FdwRoutine *fdwroutine = makeNode(FdwRoutine);
176 :
177 30 : fdwroutine->GetForeignRelSize = fileGetForeignRelSize;
178 30 : fdwroutine->GetForeignPaths = fileGetForeignPaths;
179 30 : fdwroutine->GetForeignPlan = fileGetForeignPlan;
180 30 : fdwroutine->ExplainForeignScan = fileExplainForeignScan;
181 30 : fdwroutine->BeginForeignScan = fileBeginForeignScan;
182 30 : fdwroutine->IterateForeignScan = fileIterateForeignScan;
183 30 : fdwroutine->ReScanForeignScan = fileReScanForeignScan;
184 30 : fdwroutine->EndForeignScan = fileEndForeignScan;
185 30 : fdwroutine->AnalyzeForeignTable = fileAnalyzeForeignTable;
186 30 : fdwroutine->IsForeignScanParallelSafe = fileIsForeignScanParallelSafe;
187 :
188 30 : PG_RETURN_POINTER(fdwroutine);
189 : }
190 :
191 : /*
192 : * Validate the generic options given to a FOREIGN DATA WRAPPER, SERVER,
193 : * USER MAPPING or FOREIGN TABLE that uses file_fdw.
194 : *
195 : * Raise an ERROR if the option or its value is considered invalid.
196 : */
197 : Datum
198 104 : file_fdw_validator(PG_FUNCTION_ARGS)
199 : {
200 104 : List *options_list = untransformRelOptions(PG_GETARG_DATUM(0));
201 104 : Oid catalog = PG_GETARG_OID(1);
202 104 : char *filename = NULL;
203 104 : DefElem *force_not_null = NULL;
204 104 : DefElem *force_null = NULL;
205 104 : List *other_options = NIL;
206 : ListCell *cell;
207 :
208 : /*
209 : * Check that only options supported by file_fdw, and allowed for the
210 : * current object type, are given.
211 : */
212 296 : foreach(cell, options_list)
213 : {
214 210 : DefElem *def = (DefElem *) lfirst(cell);
215 :
216 210 : if (!is_valid_option(def->defname, catalog))
217 : {
218 : const struct FileFdwOption *opt;
219 : const char *closest_match;
220 : ClosestMatchState match_state;
221 16 : bool has_valid_options = false;
222 :
223 : /*
224 : * Unknown option specified, complain about it. Provide a hint
225 : * with a valid option that looks similar, if there is one.
226 : */
227 16 : initClosestMatch(&match_state, def->defname, 4);
228 208 : for (opt = valid_options; opt->optname; opt++)
229 : {
230 192 : if (catalog == opt->optcontext)
231 : {
232 40 : has_valid_options = true;
233 40 : updateClosestMatch(&match_state, opt->optname);
234 : }
235 : }
236 :
237 16 : closest_match = getClosestMatch(&match_state);
238 16 : ereport(ERROR,
239 : (errcode(ERRCODE_FDW_INVALID_OPTION_NAME),
240 : errmsg("invalid option \"%s\"", def->defname),
241 : has_valid_options ? closest_match ?
242 : errhint("Perhaps you meant the option \"%s\".",
243 : closest_match) : 0 :
244 : errhint("There are no valid options in this context.")));
245 : }
246 :
247 : /*
248 : * Separate out filename, program, and column-specific options, since
249 : * ProcessCopyOptions won't accept them.
250 : */
251 194 : if (strcmp(def->defname, "filename") == 0 ||
252 170 : strcmp(def->defname, "program") == 0)
253 : {
254 24 : if (filename)
255 0 : ereport(ERROR,
256 : (errcode(ERRCODE_SYNTAX_ERROR),
257 : errmsg("conflicting or redundant options")));
258 :
259 : /*
260 : * Check permissions for changing which file or program is used by
261 : * the file_fdw.
262 : *
263 : * Only members of the role 'pg_read_server_files' are allowed to
264 : * set the 'filename' option of a file_fdw foreign table, while
265 : * only members of the role 'pg_execute_server_program' are
266 : * allowed to set the 'program' option. This is because we don't
267 : * want regular users to be able to control which file gets read
268 : * or which program gets executed.
269 : *
270 : * Putting this sort of permissions check in a validator is a bit
271 : * of a crock, but there doesn't seem to be any other place that
272 : * can enforce the check more cleanly.
273 : *
274 : * Note that the valid_options[] array disallows setting filename
275 : * and program at any options level other than foreign table ---
276 : * otherwise there'd still be a security hole.
277 : */
278 24 : if (strcmp(def->defname, "filename") == 0 &&
279 24 : !has_privs_of_role(GetUserId(), ROLE_PG_READ_SERVER_FILES))
280 2 : ereport(ERROR,
281 : (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
282 : errmsg("permission denied to set the \"%s\" option of a file_fdw foreign table",
283 : "filename"),
284 : errdetail("Only roles with privileges of the \"%s\" role may set this option.",
285 : "pg_read_server_files")));
286 :
287 22 : if (strcmp(def->defname, "program") == 0 &&
288 0 : !has_privs_of_role(GetUserId(), ROLE_PG_EXECUTE_SERVER_PROGRAM))
289 0 : ereport(ERROR,
290 : (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
291 : errmsg("permission denied to set the \"%s\" option of a file_fdw foreign table",
292 : "program"),
293 : errdetail("Only roles with privileges of the \"%s\" role may set this option.",
294 : "pg_execute_server_program")));
295 :
296 22 : filename = defGetString(def);
297 : }
298 :
299 : /*
300 : * force_not_null is a boolean option; after validation we can discard
301 : * it - it will be retrieved later in get_file_fdw_attribute_options()
302 : */
303 170 : else if (strcmp(def->defname, "force_not_null") == 0)
304 : {
305 8 : if (force_not_null)
306 0 : ereport(ERROR,
307 : (errcode(ERRCODE_SYNTAX_ERROR),
308 : errmsg("conflicting or redundant options"),
309 : errhint("Option \"force_not_null\" supplied more than once for a column.")));
310 8 : force_not_null = def;
311 : /* Don't care what the value is, as long as it's a legal boolean */
312 8 : (void) defGetBoolean(def);
313 : }
314 : /* See comments for force_not_null above */
315 162 : else if (strcmp(def->defname, "force_null") == 0)
316 : {
317 8 : if (force_null)
318 0 : ereport(ERROR,
319 : (errcode(ERRCODE_SYNTAX_ERROR),
320 : errmsg("conflicting or redundant options"),
321 : errhint("Option \"force_null\" supplied more than once for a column.")));
322 8 : force_null = def;
323 8 : (void) defGetBoolean(def);
324 : }
325 : else
326 154 : other_options = lappend(other_options, def);
327 : }
328 :
329 : /*
330 : * Now apply the core COPY code's validation logic for more checks.
331 : */
332 86 : ProcessCopyOptions(NULL, NULL, true, other_options);
333 :
334 : /*
335 : * Either filename or program option is required for file_fdw foreign
336 : * tables.
337 : */
338 46 : if (catalog == ForeignTableRelationId && filename == NULL)
339 2 : ereport(ERROR,
340 : (errcode(ERRCODE_FDW_DYNAMIC_PARAMETER_VALUE_NEEDED),
341 : errmsg("either filename or program is required for file_fdw foreign tables")));
342 :
343 44 : PG_RETURN_VOID();
344 : }
345 :
346 : /*
347 : * Check if the provided option is one of the valid options.
348 : * context is the Oid of the catalog holding the object the option is for.
349 : */
350 : static bool
351 210 : is_valid_option(const char *option, Oid context)
352 : {
353 : const struct FileFdwOption *opt;
354 :
355 1148 : for (opt = valid_options; opt->optname; opt++)
356 : {
357 1132 : if (context == opt->optcontext && strcmp(opt->optname, option) == 0)
358 194 : return true;
359 : }
360 16 : return false;
361 : }
362 :
363 : /*
364 : * Fetch the options for a file_fdw foreign table.
365 : *
366 : * We have to separate out filename/program from the other options because
367 : * those must not appear in the options list passed to the core COPY code.
368 : */
369 : static void
370 134 : fileGetOptions(Oid foreigntableid,
371 : char **filename, bool *is_program, List **other_options)
372 : {
373 : ForeignTable *table;
374 : ForeignServer *server;
375 : ForeignDataWrapper *wrapper;
376 : List *options;
377 : ListCell *lc;
378 :
379 : /*
380 : * Extract options from FDW objects. We ignore user mappings because
381 : * file_fdw doesn't have any options that can be specified there.
382 : *
383 : * (XXX Actually, given the current contents of valid_options[], there's
384 : * no point in examining anything except the foreign table's own options.
385 : * Simplify?)
386 : */
387 134 : table = GetForeignTable(foreigntableid);
388 134 : server = GetForeignServer(table->serverid);
389 134 : wrapper = GetForeignDataWrapper(server->fdwid);
390 :
391 134 : options = NIL;
392 134 : options = list_concat(options, wrapper->options);
393 134 : options = list_concat(options, server->options);
394 134 : options = list_concat(options, table->options);
395 134 : options = list_concat(options, get_file_fdw_attribute_options(foreigntableid));
396 :
397 : /*
398 : * Separate out the filename or program option (we assume there is only
399 : * one).
400 : */
401 134 : *filename = NULL;
402 134 : *is_program = false;
403 268 : foreach(lc, options)
404 : {
405 268 : DefElem *def = (DefElem *) lfirst(lc);
406 :
407 268 : if (strcmp(def->defname, "filename") == 0)
408 : {
409 134 : *filename = defGetString(def);
410 134 : options = foreach_delete_current(options, lc);
411 134 : break;
412 : }
413 134 : else if (strcmp(def->defname, "program") == 0)
414 : {
415 0 : *filename = defGetString(def);
416 0 : *is_program = true;
417 0 : options = foreach_delete_current(options, lc);
418 0 : break;
419 : }
420 : }
421 :
422 : /*
423 : * The validator should have checked that filename or program was included
424 : * in the options, but check again, just in case.
425 : */
426 134 : if (*filename == NULL)
427 0 : elog(ERROR, "either filename or program is required for file_fdw foreign tables");
428 :
429 134 : *other_options = options;
430 134 : }
431 :
432 : /*
433 : * Retrieve per-column generic options from pg_attribute and construct a list
434 : * of DefElems representing them.
435 : *
436 : * At the moment we only have "force_not_null", and "force_null",
437 : * which should each be combined into a single DefElem listing all such
438 : * columns, since that's what COPY expects.
439 : */
440 : static List *
441 134 : get_file_fdw_attribute_options(Oid relid)
442 : {
443 : Relation rel;
444 : TupleDesc tupleDesc;
445 : AttrNumber natts;
446 : AttrNumber attnum;
447 134 : List *fnncolumns = NIL;
448 134 : List *fncolumns = NIL;
449 :
450 134 : List *options = NIL;
451 :
452 134 : rel = table_open(relid, AccessShareLock);
453 134 : tupleDesc = RelationGetDescr(rel);
454 134 : natts = tupleDesc->natts;
455 :
456 : /* Retrieve FDW options for all user-defined attributes. */
457 426 : for (attnum = 1; attnum <= natts; attnum++)
458 : {
459 292 : Form_pg_attribute attr = TupleDescAttr(tupleDesc, attnum - 1);
460 : List *column_options;
461 : ListCell *lc;
462 :
463 : /* Skip dropped attributes. */
464 292 : if (attr->attisdropped)
465 0 : continue;
466 :
467 292 : column_options = GetForeignColumnOptions(relid, attnum);
468 324 : foreach(lc, column_options)
469 : {
470 32 : DefElem *def = (DefElem *) lfirst(lc);
471 :
472 32 : if (strcmp(def->defname, "force_not_null") == 0)
473 : {
474 16 : if (defGetBoolean(def))
475 : {
476 8 : char *attname = pstrdup(NameStr(attr->attname));
477 :
478 8 : fnncolumns = lappend(fnncolumns, makeString(attname));
479 : }
480 : }
481 16 : else if (strcmp(def->defname, "force_null") == 0)
482 : {
483 16 : if (defGetBoolean(def))
484 : {
485 8 : char *attname = pstrdup(NameStr(attr->attname));
486 :
487 8 : fncolumns = lappend(fncolumns, makeString(attname));
488 : }
489 : }
490 : /* maybe in future handle other column options here */
491 : }
492 : }
493 :
494 134 : table_close(rel, AccessShareLock);
495 :
496 : /*
497 : * Return DefElem only when some column(s) have force_not_null /
498 : * force_null options set
499 : */
500 134 : if (fnncolumns != NIL)
501 8 : options = lappend(options, makeDefElem("force_not_null", (Node *) fnncolumns, -1));
502 :
503 134 : if (fncolumns != NIL)
504 8 : options = lappend(options, makeDefElem("force_null", (Node *) fncolumns, -1));
505 :
506 134 : return options;
507 : }
508 :
509 : /*
510 : * fileGetForeignRelSize
511 : * Obtain relation size estimates for a foreign table
512 : */
513 : static void
514 72 : fileGetForeignRelSize(PlannerInfo *root,
515 : RelOptInfo *baserel,
516 : Oid foreigntableid)
517 : {
518 : FileFdwPlanState *fdw_private;
519 :
520 : /*
521 : * Fetch options. We only need filename (or program) at this point, but
522 : * we might as well get everything and not need to re-fetch it later in
523 : * planning.
524 : */
525 72 : fdw_private = (FileFdwPlanState *) palloc(sizeof(FileFdwPlanState));
526 72 : fileGetOptions(foreigntableid,
527 : &fdw_private->filename,
528 : &fdw_private->is_program,
529 : &fdw_private->options);
530 72 : baserel->fdw_private = (void *) fdw_private;
531 :
532 : /* Estimate relation size */
533 72 : estimate_size(root, baserel, fdw_private);
534 72 : }
535 :
536 : /*
537 : * fileGetForeignPaths
538 : * Create possible access paths for a scan on the foreign table
539 : *
540 : * Currently we don't support any push-down feature, so there is only one
541 : * possible access path, which simply returns all records in the order in
542 : * the data file.
543 : */
544 : static void
545 72 : fileGetForeignPaths(PlannerInfo *root,
546 : RelOptInfo *baserel,
547 : Oid foreigntableid)
548 : {
549 72 : FileFdwPlanState *fdw_private = (FileFdwPlanState *) baserel->fdw_private;
550 : Cost startup_cost;
551 : Cost total_cost;
552 : List *columns;
553 72 : List *coptions = NIL;
554 :
555 : /* Decide whether to selectively perform binary conversion */
556 72 : if (check_selective_binary_conversion(baserel,
557 : foreigntableid,
558 : &columns))
559 8 : coptions = list_make1(makeDefElem("convert_selectively",
560 : (Node *) columns, -1));
561 :
562 : /* Estimate costs */
563 72 : estimate_costs(root, baserel, fdw_private,
564 : &startup_cost, &total_cost);
565 :
566 : /*
567 : * Create a ForeignPath node and add it as only possible path. We use the
568 : * fdw_private list of the path to carry the convert_selectively option;
569 : * it will be propagated into the fdw_private list of the Plan node.
570 : *
571 : * We don't support pushing join clauses into the quals of this path, but
572 : * it could still have required parameterization due to LATERAL refs in
573 : * its tlist.
574 : */
575 72 : add_path(baserel, (Path *)
576 72 : create_foreignscan_path(root, baserel,
577 : NULL, /* default pathtarget */
578 : baserel->rows,
579 : startup_cost,
580 : total_cost,
581 : NIL, /* no pathkeys */
582 : baserel->lateral_relids,
583 : NULL, /* no extra plan */
584 : NIL, /* no fdw_restrictinfo list */
585 : coptions));
586 :
587 : /*
588 : * If data file was sorted, and we knew it somehow, we could insert
589 : * appropriate pathkeys into the ForeignPath node to tell the planner
590 : * that.
591 : */
592 72 : }
593 :
594 : /*
595 : * fileGetForeignPlan
596 : * Create a ForeignScan plan node for scanning the foreign table
597 : */
598 : static ForeignScan *
599 72 : fileGetForeignPlan(PlannerInfo *root,
600 : RelOptInfo *baserel,
601 : Oid foreigntableid,
602 : ForeignPath *best_path,
603 : List *tlist,
604 : List *scan_clauses,
605 : Plan *outer_plan)
606 : {
607 72 : Index scan_relid = baserel->relid;
608 :
609 : /*
610 : * We have no native ability to evaluate restriction clauses, so we just
611 : * put all the scan_clauses into the plan node's qual list for the
612 : * executor to check. So all we have to do here is strip RestrictInfo
613 : * nodes from the clauses and ignore pseudoconstants (which will be
614 : * handled elsewhere).
615 : */
616 72 : scan_clauses = extract_actual_clauses(scan_clauses, false);
617 :
618 : /* Create the ForeignScan node */
619 72 : return make_foreignscan(tlist,
620 : scan_clauses,
621 : scan_relid,
622 : NIL, /* no expressions to evaluate */
623 : best_path->fdw_private,
624 : NIL, /* no custom tlist */
625 : NIL, /* no remote quals */
626 : outer_plan);
627 : }
628 :
629 : /*
630 : * fileExplainForeignScan
631 : * Produce extra output for EXPLAIN
632 : */
633 : static void
634 6 : fileExplainForeignScan(ForeignScanState *node, ExplainState *es)
635 : {
636 : char *filename;
637 : bool is_program;
638 : List *options;
639 :
640 : /* Fetch options --- we only need filename and is_program at this point */
641 6 : fileGetOptions(RelationGetRelid(node->ss.ss_currentRelation),
642 : &filename, &is_program, &options);
643 :
644 6 : if (is_program)
645 0 : ExplainPropertyText("Foreign Program", filename, es);
646 : else
647 6 : ExplainPropertyText("Foreign File", filename, es);
648 :
649 : /* Suppress file size if we're not showing cost details */
650 6 : if (es->costs)
651 : {
652 : struct stat stat_buf;
653 :
654 0 : if (!is_program &&
655 0 : stat(filename, &stat_buf) == 0)
656 0 : ExplainPropertyInteger("Foreign File Size", "b",
657 0 : (int64) stat_buf.st_size, es);
658 : }
659 6 : }
660 :
661 : /*
662 : * fileBeginForeignScan
663 : * Initiate access to the file by creating CopyState
664 : */
665 : static void
666 62 : fileBeginForeignScan(ForeignScanState *node, int eflags)
667 : {
668 62 : ForeignScan *plan = (ForeignScan *) node->ss.ps.plan;
669 : char *filename;
670 : bool is_program;
671 : List *options;
672 : CopyFromState cstate;
673 : FileFdwExecutionState *festate;
674 :
675 : /*
676 : * Do nothing in EXPLAIN (no ANALYZE) case. node->fdw_state stays NULL.
677 : */
678 62 : if (eflags & EXEC_FLAG_EXPLAIN_ONLY)
679 6 : return;
680 :
681 : /* Fetch options of foreign table */
682 56 : fileGetOptions(RelationGetRelid(node->ss.ss_currentRelation),
683 : &filename, &is_program, &options);
684 :
685 : /* Add any options from the plan (currently only convert_selectively) */
686 56 : options = list_concat(options, plan->fdw_private);
687 :
688 : /*
689 : * Create CopyState from FDW options. We always acquire all columns, so
690 : * as to match the expected ScanTupleSlot signature.
691 : */
692 56 : cstate = BeginCopyFrom(NULL,
693 : node->ss.ss_currentRelation,
694 : NULL,
695 : filename,
696 : is_program,
697 : NULL,
698 : NIL,
699 : options);
700 :
701 : /*
702 : * Save state in node->fdw_state. We must save enough information to call
703 : * BeginCopyFrom() again.
704 : */
705 54 : festate = (FileFdwExecutionState *) palloc(sizeof(FileFdwExecutionState));
706 54 : festate->filename = filename;
707 54 : festate->is_program = is_program;
708 54 : festate->options = options;
709 54 : festate->cstate = cstate;
710 :
711 54 : node->fdw_state = (void *) festate;
712 : }
713 :
714 : /*
715 : * fileIterateForeignScan
716 : * Read next record from the data file and store it into the
717 : * ScanTupleSlot as a virtual tuple
718 : */
719 : static TupleTableSlot *
720 222 : fileIterateForeignScan(ForeignScanState *node)
721 : {
722 222 : FileFdwExecutionState *festate = (FileFdwExecutionState *) node->fdw_state;
723 222 : EState *estate = CreateExecutorState();
724 : ExprContext *econtext;
725 : MemoryContext oldcontext;
726 222 : TupleTableSlot *slot = node->ss.ss_ScanTupleSlot;
727 : bool found;
728 : ErrorContextCallback errcallback;
729 :
730 : /* Set up callback to identify error line number. */
731 222 : errcallback.callback = CopyFromErrorCallback;
732 222 : errcallback.arg = (void *) festate->cstate;
733 222 : errcallback.previous = error_context_stack;
734 222 : error_context_stack = &errcallback;
735 :
736 : /*
737 : * The protocol for loading a virtual tuple into a slot is first
738 : * ExecClearTuple, then fill the values/isnull arrays, then
739 : * ExecStoreVirtualTuple. If we don't find another row in the file, we
740 : * just skip the last step, leaving the slot empty as required.
741 : *
742 : * We pass ExprContext because there might be a use of the DEFAULT option
743 : * in COPY FROM, so we may need to evaluate default expressions.
744 : */
745 222 : ExecClearTuple(slot);
746 222 : econtext = GetPerTupleExprContext(estate);
747 :
748 : /*
749 : * DEFAULT expressions need to be evaluated in a per-tuple context, so
750 : * switch in case we are doing that.
751 : */
752 222 : oldcontext = MemoryContextSwitchTo(GetPerTupleMemoryContext(estate));
753 222 : found = NextCopyFrom(festate->cstate, econtext,
754 : slot->tts_values, slot->tts_isnull);
755 218 : if (found)
756 164 : ExecStoreVirtualTuple(slot);
757 :
758 : /* Switch back to original memory context */
759 218 : MemoryContextSwitchTo(oldcontext);
760 :
761 : /* Remove error callback. */
762 218 : error_context_stack = errcallback.previous;
763 :
764 218 : return slot;
765 : }
766 :
767 : /*
768 : * fileReScanForeignScan
769 : * Rescan table, possibly with new parameters
770 : */
771 : static void
772 6 : fileReScanForeignScan(ForeignScanState *node)
773 : {
774 6 : FileFdwExecutionState *festate = (FileFdwExecutionState *) node->fdw_state;
775 :
776 6 : EndCopyFrom(festate->cstate);
777 :
778 12 : festate->cstate = BeginCopyFrom(NULL,
779 : node->ss.ss_currentRelation,
780 : NULL,
781 6 : festate->filename,
782 6 : festate->is_program,
783 : NULL,
784 : NIL,
785 : festate->options);
786 6 : }
787 :
788 : /*
789 : * fileEndForeignScan
790 : * Finish scanning foreign table and dispose objects used for this scan
791 : */
792 : static void
793 56 : fileEndForeignScan(ForeignScanState *node)
794 : {
795 56 : FileFdwExecutionState *festate = (FileFdwExecutionState *) node->fdw_state;
796 :
797 : /* if festate is NULL, we are in EXPLAIN; nothing to do */
798 56 : if (festate)
799 50 : EndCopyFrom(festate->cstate);
800 56 : }
801 :
802 : /*
803 : * fileAnalyzeForeignTable
804 : * Test whether analyzing this foreign table is supported
805 : */
806 : static bool
807 0 : fileAnalyzeForeignTable(Relation relation,
808 : AcquireSampleRowsFunc *func,
809 : BlockNumber *totalpages)
810 : {
811 : char *filename;
812 : bool is_program;
813 : List *options;
814 : struct stat stat_buf;
815 :
816 : /* Fetch options of foreign table */
817 0 : fileGetOptions(RelationGetRelid(relation), &filename, &is_program, &options);
818 :
819 : /*
820 : * If this is a program instead of a file, just return false to skip
821 : * analyzing the table. We could run the program and collect stats on
822 : * whatever it currently returns, but it seems likely that in such cases
823 : * the output would be too volatile for the stats to be useful. Maybe
824 : * there should be an option to enable doing this?
825 : */
826 0 : if (is_program)
827 0 : return false;
828 :
829 : /*
830 : * Get size of the file. (XXX if we fail here, would it be better to just
831 : * return false to skip analyzing the table?)
832 : */
833 0 : if (stat(filename, &stat_buf) < 0)
834 0 : ereport(ERROR,
835 : (errcode_for_file_access(),
836 : errmsg("could not stat file \"%s\": %m",
837 : filename)));
838 :
839 : /*
840 : * Convert size to pages. Must return at least 1 so that we can tell
841 : * later on that pg_class.relpages is not default.
842 : */
843 0 : *totalpages = (stat_buf.st_size + (BLCKSZ - 1)) / BLCKSZ;
844 0 : if (*totalpages < 1)
845 0 : *totalpages = 1;
846 :
847 0 : *func = file_acquire_sample_rows;
848 :
849 0 : return true;
850 : }
851 :
852 : /*
853 : * fileIsForeignScanParallelSafe
854 : * Reading a file, or external program, in a parallel worker should work
855 : * just the same as reading it in the leader, so mark scans safe.
856 : */
857 : static bool
858 64 : fileIsForeignScanParallelSafe(PlannerInfo *root, RelOptInfo *rel,
859 : RangeTblEntry *rte)
860 : {
861 64 : return true;
862 : }
863 :
864 : /*
865 : * check_selective_binary_conversion
866 : *
867 : * Check to see if it's useful to convert only a subset of the file's columns
868 : * to binary. If so, construct a list of the column names to be converted,
869 : * return that at *columns, and return true. (Note that it's possible to
870 : * determine that no columns need be converted, for instance with a COUNT(*)
871 : * query. So we can't use returning a NIL list to indicate failure.)
872 : */
873 : static bool
874 72 : check_selective_binary_conversion(RelOptInfo *baserel,
875 : Oid foreigntableid,
876 : List **columns)
877 : {
878 : ForeignTable *table;
879 : ListCell *lc;
880 : Relation rel;
881 : TupleDesc tupleDesc;
882 : int attidx;
883 72 : Bitmapset *attrs_used = NULL;
884 72 : bool has_wholerow = false;
885 : int numattrs;
886 : int i;
887 :
888 72 : *columns = NIL; /* default result */
889 :
890 : /*
891 : * Check format of the file. If binary format, this is irrelevant.
892 : */
893 72 : table = GetForeignTable(foreigntableid);
894 72 : foreach(lc, table->options)
895 : {
896 72 : DefElem *def = (DefElem *) lfirst(lc);
897 :
898 72 : if (strcmp(def->defname, "format") == 0)
899 : {
900 72 : char *format = defGetString(def);
901 :
902 72 : if (strcmp(format, "binary") == 0)
903 0 : return false;
904 72 : break;
905 : }
906 : }
907 :
908 : /* Collect all the attributes needed for joins or final output. */
909 72 : pull_varattnos((Node *) baserel->reltarget->exprs, baserel->relid,
910 : &attrs_used);
911 :
912 : /* Add all the attributes used by restriction clauses. */
913 88 : foreach(lc, baserel->baserestrictinfo)
914 : {
915 16 : RestrictInfo *rinfo = (RestrictInfo *) lfirst(lc);
916 :
917 16 : pull_varattnos((Node *) rinfo->clause, baserel->relid,
918 : &attrs_used);
919 : }
920 :
921 : /* Convert attribute numbers to column names. */
922 72 : rel = table_open(foreigntableid, AccessShareLock);
923 72 : tupleDesc = RelationGetDescr(rel);
924 :
925 72 : attidx = -1;
926 230 : while ((attidx = bms_next_member(attrs_used, attidx)) >= 0)
927 : {
928 : /* attidx is zero-based, attnum is the normal attribute number */
929 166 : AttrNumber attnum = attidx + FirstLowInvalidHeapAttributeNumber;
930 :
931 166 : if (attnum == 0)
932 : {
933 8 : has_wholerow = true;
934 8 : break;
935 : }
936 :
937 : /* Ignore system attributes. */
938 158 : if (attnum < 0)
939 26 : continue;
940 :
941 : /* Get user attributes. */
942 132 : if (attnum > 0)
943 : {
944 132 : Form_pg_attribute attr = TupleDescAttr(tupleDesc, attnum - 1);
945 132 : char *attname = NameStr(attr->attname);
946 :
947 : /* Skip dropped attributes (probably shouldn't see any here). */
948 132 : if (attr->attisdropped)
949 0 : continue;
950 :
951 : /*
952 : * Skip generated columns (COPY won't accept them in the column
953 : * list)
954 : */
955 132 : if (attr->attgenerated)
956 2 : continue;
957 130 : *columns = lappend(*columns, makeString(pstrdup(attname)));
958 : }
959 : }
960 :
961 : /* Count non-dropped user attributes while we have the tupdesc. */
962 72 : numattrs = 0;
963 228 : for (i = 0; i < tupleDesc->natts; i++)
964 : {
965 156 : Form_pg_attribute attr = TupleDescAttr(tupleDesc, i);
966 :
967 156 : if (attr->attisdropped)
968 0 : continue;
969 156 : numattrs++;
970 : }
971 :
972 72 : table_close(rel, AccessShareLock);
973 :
974 : /* If there's a whole-row reference, fail: we need all the columns. */
975 72 : if (has_wholerow)
976 : {
977 8 : *columns = NIL;
978 8 : return false;
979 : }
980 :
981 : /* If all the user attributes are needed, fail. */
982 64 : if (numattrs == list_length(*columns))
983 : {
984 56 : *columns = NIL;
985 56 : return false;
986 : }
987 :
988 8 : return true;
989 : }
990 :
991 : /*
992 : * Estimate size of a foreign table.
993 : *
994 : * The main result is returned in baserel->rows. We also set
995 : * fdw_private->pages and fdw_private->ntuples for later use in the cost
996 : * calculation.
997 : */
998 : static void
999 72 : estimate_size(PlannerInfo *root, RelOptInfo *baserel,
1000 : FileFdwPlanState *fdw_private)
1001 : {
1002 : struct stat stat_buf;
1003 : BlockNumber pages;
1004 : double ntuples;
1005 : double nrows;
1006 :
1007 : /*
1008 : * Get size of the file. It might not be there at plan time, though, in
1009 : * which case we have to use a default estimate. We also have to fall
1010 : * back to the default if using a program as the input.
1011 : */
1012 72 : if (fdw_private->is_program || stat(fdw_private->filename, &stat_buf) < 0)
1013 0 : stat_buf.st_size = 10 * BLCKSZ;
1014 :
1015 : /*
1016 : * Convert size to pages for use in I/O cost estimate later.
1017 : */
1018 72 : pages = (stat_buf.st_size + (BLCKSZ - 1)) / BLCKSZ;
1019 72 : if (pages < 1)
1020 0 : pages = 1;
1021 72 : fdw_private->pages = pages;
1022 :
1023 : /*
1024 : * Estimate the number of tuples in the file.
1025 : */
1026 72 : if (baserel->tuples >= 0 && baserel->pages > 0)
1027 0 : {
1028 : /*
1029 : * We have # of pages and # of tuples from pg_class (that is, from a
1030 : * previous ANALYZE), so compute a tuples-per-page estimate and scale
1031 : * that by the current file size.
1032 : */
1033 : double density;
1034 :
1035 0 : density = baserel->tuples / (double) baserel->pages;
1036 0 : ntuples = clamp_row_est(density * (double) pages);
1037 : }
1038 : else
1039 : {
1040 : /*
1041 : * Otherwise we have to fake it. We back into this estimate using the
1042 : * planner's idea of the relation width; which is bogus if not all
1043 : * columns are being read, not to mention that the text representation
1044 : * of a row probably isn't the same size as its internal
1045 : * representation. Possibly we could do something better, but the
1046 : * real answer to anyone who complains is "ANALYZE" ...
1047 : */
1048 : int tuple_width;
1049 :
1050 72 : tuple_width = MAXALIGN(baserel->reltarget->width) +
1051 : MAXALIGN(SizeofHeapTupleHeader);
1052 72 : ntuples = clamp_row_est((double) stat_buf.st_size /
1053 72 : (double) tuple_width);
1054 : }
1055 72 : fdw_private->ntuples = ntuples;
1056 :
1057 : /*
1058 : * Now estimate the number of rows returned by the scan after applying the
1059 : * baserestrictinfo quals.
1060 : */
1061 72 : nrows = ntuples *
1062 72 : clauselist_selectivity(root,
1063 : baserel->baserestrictinfo,
1064 : 0,
1065 : JOIN_INNER,
1066 : NULL);
1067 :
1068 72 : nrows = clamp_row_est(nrows);
1069 :
1070 : /* Save the output-rows estimate for the planner */
1071 72 : baserel->rows = nrows;
1072 72 : }
1073 :
1074 : /*
1075 : * Estimate costs of scanning a foreign table.
1076 : *
1077 : * Results are returned in *startup_cost and *total_cost.
1078 : */
1079 : static void
1080 72 : estimate_costs(PlannerInfo *root, RelOptInfo *baserel,
1081 : FileFdwPlanState *fdw_private,
1082 : Cost *startup_cost, Cost *total_cost)
1083 : {
1084 72 : BlockNumber pages = fdw_private->pages;
1085 72 : double ntuples = fdw_private->ntuples;
1086 72 : Cost run_cost = 0;
1087 : Cost cpu_per_tuple;
1088 :
1089 : /*
1090 : * We estimate costs almost the same way as cost_seqscan(), thus assuming
1091 : * that I/O costs are equivalent to a regular table file of the same size.
1092 : * However, we take per-tuple CPU costs as 10x of a seqscan, to account
1093 : * for the cost of parsing records.
1094 : *
1095 : * In the case of a program source, this calculation is even more divorced
1096 : * from reality, but we have no good alternative; and it's not clear that
1097 : * the numbers we produce here matter much anyway, since there's only one
1098 : * access path for the rel.
1099 : */
1100 72 : run_cost += seq_page_cost * pages;
1101 :
1102 72 : *startup_cost = baserel->baserestrictcost.startup;
1103 72 : cpu_per_tuple = cpu_tuple_cost * 10 + baserel->baserestrictcost.per_tuple;
1104 72 : run_cost += cpu_per_tuple * ntuples;
1105 72 : *total_cost = *startup_cost + run_cost;
1106 72 : }
1107 :
1108 : /*
1109 : * file_acquire_sample_rows -- acquire a random sample of rows from the table
1110 : *
1111 : * Selected rows are returned in the caller-allocated array rows[],
1112 : * which must have at least targrows entries.
1113 : * The actual number of rows selected is returned as the function result.
1114 : * We also count the total number of rows in the file and return it into
1115 : * *totalrows. Note that *totaldeadrows is always set to 0.
1116 : *
1117 : * Note that the returned list of rows is not always in order by physical
1118 : * position in the file. Therefore, correlation estimates derived later
1119 : * may be meaningless, but it's OK because we don't use the estimates
1120 : * currently (the planner only pays attention to correlation for indexscans).
1121 : */
1122 : static int
1123 0 : file_acquire_sample_rows(Relation onerel, int elevel,
1124 : HeapTuple *rows, int targrows,
1125 : double *totalrows, double *totaldeadrows)
1126 : {
1127 0 : int numrows = 0;
1128 0 : double rowstoskip = -1; /* -1 means not set yet */
1129 : ReservoirStateData rstate;
1130 : TupleDesc tupDesc;
1131 : Datum *values;
1132 : bool *nulls;
1133 : bool found;
1134 : char *filename;
1135 : bool is_program;
1136 : List *options;
1137 : CopyFromState cstate;
1138 : ErrorContextCallback errcallback;
1139 0 : MemoryContext oldcontext = CurrentMemoryContext;
1140 : MemoryContext tupcontext;
1141 :
1142 : Assert(onerel);
1143 : Assert(targrows > 0);
1144 :
1145 0 : tupDesc = RelationGetDescr(onerel);
1146 0 : values = (Datum *) palloc(tupDesc->natts * sizeof(Datum));
1147 0 : nulls = (bool *) palloc(tupDesc->natts * sizeof(bool));
1148 :
1149 : /* Fetch options of foreign table */
1150 0 : fileGetOptions(RelationGetRelid(onerel), &filename, &is_program, &options);
1151 :
1152 : /*
1153 : * Create CopyState from FDW options.
1154 : */
1155 0 : cstate = BeginCopyFrom(NULL, onerel, NULL, filename, is_program, NULL, NIL,
1156 : options);
1157 :
1158 : /*
1159 : * Use per-tuple memory context to prevent leak of memory used to read
1160 : * rows from the file with Copy routines.
1161 : */
1162 0 : tupcontext = AllocSetContextCreate(CurrentMemoryContext,
1163 : "file_fdw temporary context",
1164 : ALLOCSET_DEFAULT_SIZES);
1165 :
1166 : /* Prepare for sampling rows */
1167 0 : reservoir_init_selection_state(&rstate, targrows);
1168 :
1169 : /* Set up callback to identify error line number. */
1170 0 : errcallback.callback = CopyFromErrorCallback;
1171 0 : errcallback.arg = (void *) cstate;
1172 0 : errcallback.previous = error_context_stack;
1173 0 : error_context_stack = &errcallback;
1174 :
1175 0 : *totalrows = 0;
1176 0 : *totaldeadrows = 0;
1177 : for (;;)
1178 : {
1179 : /* Check for user-requested abort or sleep */
1180 0 : vacuum_delay_point();
1181 :
1182 : /* Fetch next row */
1183 0 : MemoryContextReset(tupcontext);
1184 0 : MemoryContextSwitchTo(tupcontext);
1185 :
1186 0 : found = NextCopyFrom(cstate, NULL, values, nulls);
1187 :
1188 0 : MemoryContextSwitchTo(oldcontext);
1189 :
1190 0 : if (!found)
1191 0 : break;
1192 :
1193 : /*
1194 : * The first targrows sample rows are simply copied into the
1195 : * reservoir. Then we start replacing tuples in the sample until we
1196 : * reach the end of the relation. This algorithm is from Jeff Vitter's
1197 : * paper (see more info in commands/analyze.c).
1198 : */
1199 0 : if (numrows < targrows)
1200 : {
1201 0 : rows[numrows++] = heap_form_tuple(tupDesc, values, nulls);
1202 : }
1203 : else
1204 : {
1205 : /*
1206 : * t in Vitter's paper is the number of records already processed.
1207 : * If we need to compute a new S value, we must use the
1208 : * not-yet-incremented value of totalrows as t.
1209 : */
1210 0 : if (rowstoskip < 0)
1211 0 : rowstoskip = reservoir_get_next_S(&rstate, *totalrows, targrows);
1212 :
1213 0 : if (rowstoskip <= 0)
1214 : {
1215 : /*
1216 : * Found a suitable tuple, so save it, replacing one old tuple
1217 : * at random
1218 : */
1219 0 : int k = (int) (targrows * sampler_random_fract(&rstate.randstate));
1220 :
1221 : Assert(k >= 0 && k < targrows);
1222 0 : heap_freetuple(rows[k]);
1223 0 : rows[k] = heap_form_tuple(tupDesc, values, nulls);
1224 : }
1225 :
1226 0 : rowstoskip -= 1;
1227 : }
1228 :
1229 0 : *totalrows += 1;
1230 : }
1231 :
1232 : /* Remove error callback. */
1233 0 : error_context_stack = errcallback.previous;
1234 :
1235 : /* Clean up. */
1236 0 : MemoryContextDelete(tupcontext);
1237 :
1238 0 : EndCopyFrom(cstate);
1239 :
1240 0 : pfree(values);
1241 0 : pfree(nulls);
1242 :
1243 : /*
1244 : * Emit some interesting relation info
1245 : */
1246 0 : ereport(elevel,
1247 : (errmsg("\"%s\": file contains %.0f rows; "
1248 : "%d rows in sample",
1249 : RelationGetRelationName(onerel),
1250 : *totalrows, numrows)));
1251 :
1252 0 : return numrows;
1253 : }
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