diff options
Diffstat (limited to 'contrib/file_fdw/file_fdw.c')
| -rw-r--r-- | contrib/file_fdw/file_fdw.c | 131 |
1 files changed, 88 insertions, 43 deletions
diff --git a/contrib/file_fdw/file_fdw.c b/contrib/file_fdw/file_fdw.c index b4719913183..d325f534676 100644 --- a/contrib/file_fdw/file_fdw.c +++ b/contrib/file_fdw/file_fdw.c @@ -1,7 +1,7 @@ /*------------------------------------------------------------------------- * * file_fdw.c - * foreign-data wrapper for server-side flat files. + * foreign-data wrapper for server-side flat files (or programs). * * Copyright (c) 2010-2016, PostgreSQL Global Development Group * @@ -57,8 +57,9 @@ struct FileFdwOption * fileGetOptions(), which currently doesn't bother to look at user mappings. */ static const struct FileFdwOption valid_options[] = { - /* File options */ + /* Data source options */ {"filename", ForeignTableRelationId}, + {"program", ForeignTableRelationId}, /* Format options */ /* oids option is not supported */ @@ -85,10 +86,12 @@ static const struct FileFdwOption valid_options[] = { */ typedef struct FileFdwPlanState { - char *filename; /* file to read */ - List *options; /* merged COPY options, excluding filename */ + char *filename; /* file or program to read from */ + bool is_program; /* true if filename represents an OS command */ + List *options; /* merged COPY options, excluding filename and + * is_program */ BlockNumber pages; /* estimate of file's physical size */ - double ntuples; /* estimate of number of rows in file */ + double ntuples; /* estimate of number of data rows */ } FileFdwPlanState; /* @@ -96,9 +99,11 @@ typedef struct FileFdwPlanState */ typedef struct FileFdwExecutionState { - char *filename; /* file to read */ - List *options; /* merged COPY options, excluding filename */ - CopyState cstate; /* state of reading file */ + char *filename; /* file or program to read from */ + bool is_program; /* true if filename represents an OS command */ + List *options; /* merged COPY options, excluding filename and + * is_program */ + CopyState cstate; /* COPY execution state */ } FileFdwExecutionState; /* @@ -139,7 +144,9 @@ static bool fileIsForeignScanParallelSafe(PlannerInfo *root, RelOptInfo *rel, */ static bool is_valid_option(const char *option, Oid context); static void fileGetOptions(Oid foreigntableid, - char **filename, List **other_options); + char **filename, + bool *is_program, + List **other_options); static List *get_file_fdw_attribute_options(Oid relid); static bool check_selective_binary_conversion(RelOptInfo *baserel, Oid foreigntableid, @@ -196,16 +203,16 @@ file_fdw_validator(PG_FUNCTION_ARGS) /* * Only superusers are allowed to set options of a file_fdw foreign table. - * This is because the filename is one of those options, and we don't want - * non-superusers to be able to determine which file gets read. + * This is because we don't want non-superusers to be able to control + * which file gets read or which program gets executed. * * Putting this sort of permissions check in a validator is a bit of a * crock, but there doesn't seem to be any other place that can enforce * the check more cleanly. * - * Note that the valid_options[] array disallows setting filename at any - * options level other than foreign table --- otherwise there'd still be a - * security hole. + * Note that the valid_options[] array disallows setting filename and + * program at any options level other than foreign table --- otherwise + * there'd still be a security hole. */ if (catalog == ForeignTableRelationId && !superuser()) ereport(ERROR, @@ -247,11 +254,11 @@ file_fdw_validator(PG_FUNCTION_ARGS) } /* - * Separate out filename and column-specific options, since + * Separate out filename, program, and column-specific options, since * ProcessCopyOptions won't accept them. */ - - if (strcmp(def->defname, "filename") == 0) + if (strcmp(def->defname, "filename") == 0 || + strcmp(def->defname, "program") == 0) { if (filename) ereport(ERROR, @@ -296,12 +303,13 @@ file_fdw_validator(PG_FUNCTION_ARGS) ProcessCopyOptions(NULL, NULL, true, other_options); /* - * Filename option is required for file_fdw foreign tables. + * Either filename or program option is required for file_fdw foreign + * tables. */ if (catalog == ForeignTableRelationId && filename == NULL) ereport(ERROR, (errcode(ERRCODE_FDW_DYNAMIC_PARAMETER_VALUE_NEEDED), - errmsg("filename is required for file_fdw foreign tables"))); + errmsg("either filename or program is required for file_fdw foreign tables"))); PG_RETURN_VOID(); } @@ -326,12 +334,12 @@ is_valid_option(const char *option, Oid context) /* * Fetch the options for a file_fdw foreign table. * - * We have to separate out "filename" from the other options because - * it must not appear in the options list passed to the core COPY code. + * We have to separate out filename/program from the other options because + * those must not appear in the options list passed to the core COPY code. */ static void fileGetOptions(Oid foreigntableid, - char **filename, List **other_options) + char **filename, bool *is_program, List **other_options) { ForeignTable *table; ForeignServer *server; @@ -359,9 +367,11 @@ fileGetOptions(Oid foreigntableid, options = list_concat(options, get_file_fdw_attribute_options(foreigntableid)); /* - * Separate out the filename. + * Separate out the filename or program option (we assume there is only + * one). */ *filename = NULL; + *is_program = false; prev = NULL; foreach(lc, options) { @@ -373,15 +383,22 @@ fileGetOptions(Oid foreigntableid, options = list_delete_cell(options, lc, prev); break; } + else if (strcmp(def->defname, "program") == 0) + { + *filename = defGetString(def); + *is_program = true; + options = list_delete_cell(options, lc, prev); + break; + } prev = lc; } /* - * The validator should have checked that a filename was included in the - * options, but check again, just in case. + * The validator should have checked that filename or program was included + * in the options, but check again, just in case. */ if (*filename == NULL) - elog(ERROR, "filename is required for file_fdw foreign tables"); + elog(ERROR, "either filename or program is required for file_fdw foreign tables"); *other_options = options; } @@ -475,12 +492,15 @@ fileGetForeignRelSize(PlannerInfo *root, FileFdwPlanState *fdw_private; /* - * Fetch options. We only need filename at this point, but we might as - * well get everything and not need to re-fetch it later in planning. + * Fetch options. We only need filename (or program) at this point, but + * we might as well get everything and not need to re-fetch it later in + * planning. */ fdw_private = (FileFdwPlanState *) palloc(sizeof(FileFdwPlanState)); fileGetOptions(foreigntableid, - &fdw_private->filename, &fdw_private->options); + &fdw_private->filename, + &fdw_private->is_program, + &fdw_private->options); baserel->fdw_private = (void *) fdw_private; /* Estimate relation size */ @@ -583,20 +603,25 @@ static void fileExplainForeignScan(ForeignScanState *node, ExplainState *es) { char *filename; + bool is_program; List *options; - /* Fetch options --- we only need filename at this point */ + /* Fetch options --- we only need filename and is_program at this point */ fileGetOptions(RelationGetRelid(node->ss.ss_currentRelation), - &filename, &options); + &filename, &is_program, &options); - ExplainPropertyText("Foreign File", filename, es); + if (is_program) + ExplainPropertyText("Foreign Program", filename, es); + else + ExplainPropertyText("Foreign File", filename, es); /* Suppress file size if we're not showing cost details */ if (es->costs) { struct stat stat_buf; - if (stat(filename, &stat_buf) == 0) + if (!is_program && + stat(filename, &stat_buf) == 0) ExplainPropertyLong("Foreign File Size", (long) stat_buf.st_size, es); } @@ -611,6 +636,7 @@ fileBeginForeignScan(ForeignScanState *node, int eflags) { ForeignScan *plan = (ForeignScan *) node->ss.ps.plan; char *filename; + bool is_program; List *options; CopyState cstate; FileFdwExecutionState *festate; @@ -623,7 +649,7 @@ fileBeginForeignScan(ForeignScanState *node, int eflags) /* Fetch options of foreign table */ fileGetOptions(RelationGetRelid(node->ss.ss_currentRelation), - &filename, &options); + &filename, &is_program, &options); /* Add any options from the plan (currently only convert_selectively) */ options = list_concat(options, plan->fdw_private); @@ -635,7 +661,7 @@ fileBeginForeignScan(ForeignScanState *node, int eflags) cstate = BeginCopyFrom(NULL, node->ss.ss_currentRelation, filename, - false, + is_program, NIL, options); @@ -645,6 +671,7 @@ fileBeginForeignScan(ForeignScanState *node, int eflags) */ festate = (FileFdwExecutionState *) palloc(sizeof(FileFdwExecutionState)); festate->filename = filename; + festate->is_program = is_program; festate->options = options; festate->cstate = cstate; @@ -709,7 +736,7 @@ fileReScanForeignScan(ForeignScanState *node) festate->cstate = BeginCopyFrom(NULL, node->ss.ss_currentRelation, festate->filename, - false, + festate->is_program, NIL, festate->options); } @@ -738,11 +765,22 @@ fileAnalyzeForeignTable(Relation relation, BlockNumber *totalpages) { char *filename; + bool is_program; List *options; struct stat stat_buf; /* Fetch options of foreign table */ - fileGetOptions(RelationGetRelid(relation), &filename, &options); + fileGetOptions(RelationGetRelid(relation), &filename, &is_program, &options); + + /* + * If this is a program instead of a file, just return false to skip + * analyzing the table. We could run the program and collect stats on + * whatever it currently returns, but it seems likely that in such cases + * the output would be too volatile for the stats to be useful. Maybe + * there should be an option to enable doing this? + */ + if (is_program) + return false; /* * Get size of the file. (XXX if we fail here, would it be better to just @@ -769,8 +807,8 @@ fileAnalyzeForeignTable(Relation relation, /* * fileIsForeignScanParallelSafe - * Reading a file in a parallel worker should work just the same as - * reading it in the leader, so mark scans safe. + * Reading a file, or external program, in a parallel worker should work + * just the same as reading it in the leader, so mark scans safe. */ static bool fileIsForeignScanParallelSafe(PlannerInfo *root, RelOptInfo *rel, @@ -916,9 +954,10 @@ estimate_size(PlannerInfo *root, RelOptInfo *baserel, /* * Get size of the file. It might not be there at plan time, though, in - * which case we have to use a default estimate. + * which case we have to use a default estimate. We also have to fall + * back to the default if using a program as the input. */ - if (stat(fdw_private->filename, &stat_buf) < 0) + if (fdw_private->is_program || stat(fdw_private->filename, &stat_buf) < 0) stat_buf.st_size = 10 * BLCKSZ; /* @@ -1000,6 +1039,11 @@ estimate_costs(PlannerInfo *root, RelOptInfo *baserel, * that I/O costs are equivalent to a regular table file of the same size. * However, we take per-tuple CPU costs as 10x of a seqscan, to account * for the cost of parsing records. + * + * In the case of a program source, this calculation is even more divorced + * from reality, but we have no good alternative; and it's not clear that + * the numbers we produce here matter much anyway, since there's only one + * access path for the rel. */ run_cost += seq_page_cost * pages; @@ -1036,6 +1080,7 @@ file_acquire_sample_rows(Relation onerel, int elevel, bool *nulls; bool found; char *filename; + bool is_program; List *options; CopyState cstate; ErrorContextCallback errcallback; @@ -1050,12 +1095,12 @@ file_acquire_sample_rows(Relation onerel, int elevel, nulls = (bool *) palloc(tupDesc->natts * sizeof(bool)); /* Fetch options of foreign table */ - fileGetOptions(RelationGetRelid(onerel), &filename, &options); + fileGetOptions(RelationGetRelid(onerel), &filename, &is_program, &options); /* * Create CopyState from FDW options. */ - cstate = BeginCopyFrom(NULL, onerel, filename, false, NIL, options); + cstate = BeginCopyFrom(NULL, onerel, filename, is_program, NIL, options); /* * Use per-tuple memory context to prevent leak of memory used to read |