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The term 'default roles' wasn't quite apt as these roles aren't able to be modified or removed after installation, so rename them to be 'Predefined Roles' instead, adding an entry into the newly added Obsolete Appendix to help users of current releases find the new documentation. Bruce Momjian and Stephen Frost Discussion: https://postgr.es/m/157742545062.1149.11052653770497832538%40wrigleys.postgresql.org and https://www.postgresql.org/message-id/20201120211304.GG16415@tamriel.snowman.net
1226 lines
34 KiB
C
1226 lines
34 KiB
C
/*-------------------------------------------------------------------------
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*
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* file_fdw.c
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* foreign-data wrapper for server-side flat files (or programs).
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*
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* Copyright (c) 2010-2021, PostgreSQL Global Development Group
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*
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* IDENTIFICATION
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* contrib/file_fdw/file_fdw.c
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*
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*-------------------------------------------------------------------------
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*/
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#include "postgres.h"
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#include <sys/stat.h>
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#include <unistd.h>
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#include "access/htup_details.h"
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#include "access/reloptions.h"
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#include "access/sysattr.h"
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#include "access/table.h"
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#include "catalog/pg_authid.h"
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#include "catalog/pg_foreign_table.h"
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#include "commands/copy.h"
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#include "commands/defrem.h"
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#include "commands/explain.h"
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#include "commands/vacuum.h"
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#include "foreign/fdwapi.h"
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#include "foreign/foreign.h"
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#include "miscadmin.h"
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#include "nodes/makefuncs.h"
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#include "optimizer/optimizer.h"
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#include "optimizer/pathnode.h"
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#include "optimizer/planmain.h"
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#include "optimizer/restrictinfo.h"
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#include "utils/acl.h"
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#include "utils/memutils.h"
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#include "utils/rel.h"
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#include "utils/sampling.h"
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PG_MODULE_MAGIC;
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/*
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* Describes the valid options for objects that use this wrapper.
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*/
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struct FileFdwOption
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{
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const char *optname;
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Oid optcontext; /* Oid of catalog in which option may appear */
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};
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/*
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* Valid options for file_fdw.
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* These options are based on the options for the COPY FROM command.
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* But note that force_not_null and force_null are handled as boolean options
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* attached to a column, not as table options.
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*
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* Note: If you are adding new option for user mapping, you need to modify
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* fileGetOptions(), which currently doesn't bother to look at user mappings.
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*/
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static const struct FileFdwOption valid_options[] = {
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/* Data source options */
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{"filename", ForeignTableRelationId},
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{"program", ForeignTableRelationId},
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/* Format options */
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/* oids option is not supported */
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{"format", ForeignTableRelationId},
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{"header", ForeignTableRelationId},
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{"delimiter", ForeignTableRelationId},
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{"quote", ForeignTableRelationId},
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{"escape", ForeignTableRelationId},
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{"null", ForeignTableRelationId},
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{"encoding", ForeignTableRelationId},
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{"force_not_null", AttributeRelationId},
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{"force_null", AttributeRelationId},
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/*
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* force_quote is not supported by file_fdw because it's for COPY TO.
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*/
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/* Sentinel */
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{NULL, InvalidOid}
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};
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/*
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* FDW-specific information for RelOptInfo.fdw_private.
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*/
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typedef struct FileFdwPlanState
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{
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char *filename; /* file or program to read from */
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bool is_program; /* true if filename represents an OS command */
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List *options; /* merged COPY options, excluding filename and
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* is_program */
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BlockNumber pages; /* estimate of file's physical size */
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double ntuples; /* estimate of number of data rows */
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} FileFdwPlanState;
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/*
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* FDW-specific information for ForeignScanState.fdw_state.
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*/
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typedef struct FileFdwExecutionState
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{
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char *filename; /* file or program to read from */
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bool is_program; /* true if filename represents an OS command */
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List *options; /* merged COPY options, excluding filename and
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* is_program */
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CopyFromState cstate; /* COPY execution state */
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} FileFdwExecutionState;
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/*
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* SQL functions
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*/
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PG_FUNCTION_INFO_V1(file_fdw_handler);
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PG_FUNCTION_INFO_V1(file_fdw_validator);
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/*
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* FDW callback routines
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*/
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static void fileGetForeignRelSize(PlannerInfo *root,
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RelOptInfo *baserel,
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Oid foreigntableid);
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static void fileGetForeignPaths(PlannerInfo *root,
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RelOptInfo *baserel,
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Oid foreigntableid);
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static ForeignScan *fileGetForeignPlan(PlannerInfo *root,
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RelOptInfo *baserel,
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Oid foreigntableid,
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ForeignPath *best_path,
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List *tlist,
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List *scan_clauses,
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Plan *outer_plan);
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static void fileExplainForeignScan(ForeignScanState *node, ExplainState *es);
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static void fileBeginForeignScan(ForeignScanState *node, int eflags);
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static TupleTableSlot *fileIterateForeignScan(ForeignScanState *node);
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static void fileReScanForeignScan(ForeignScanState *node);
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static void fileEndForeignScan(ForeignScanState *node);
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static bool fileAnalyzeForeignTable(Relation relation,
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AcquireSampleRowsFunc *func,
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BlockNumber *totalpages);
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static bool fileIsForeignScanParallelSafe(PlannerInfo *root, RelOptInfo *rel,
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RangeTblEntry *rte);
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/*
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* Helper functions
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*/
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static bool is_valid_option(const char *option, Oid context);
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static void fileGetOptions(Oid foreigntableid,
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char **filename,
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bool *is_program,
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List **other_options);
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static List *get_file_fdw_attribute_options(Oid relid);
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static bool check_selective_binary_conversion(RelOptInfo *baserel,
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Oid foreigntableid,
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List **columns);
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static void estimate_size(PlannerInfo *root, RelOptInfo *baserel,
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FileFdwPlanState *fdw_private);
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static void estimate_costs(PlannerInfo *root, RelOptInfo *baserel,
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FileFdwPlanState *fdw_private,
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Cost *startup_cost, Cost *total_cost);
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static int file_acquire_sample_rows(Relation onerel, int elevel,
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HeapTuple *rows, int targrows,
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double *totalrows, double *totaldeadrows);
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/*
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* Foreign-data wrapper handler function: return a struct with pointers
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* to my callback routines.
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*/
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Datum
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file_fdw_handler(PG_FUNCTION_ARGS)
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{
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FdwRoutine *fdwroutine = makeNode(FdwRoutine);
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fdwroutine->GetForeignRelSize = fileGetForeignRelSize;
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fdwroutine->GetForeignPaths = fileGetForeignPaths;
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fdwroutine->GetForeignPlan = fileGetForeignPlan;
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fdwroutine->ExplainForeignScan = fileExplainForeignScan;
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fdwroutine->BeginForeignScan = fileBeginForeignScan;
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fdwroutine->IterateForeignScan = fileIterateForeignScan;
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fdwroutine->ReScanForeignScan = fileReScanForeignScan;
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fdwroutine->EndForeignScan = fileEndForeignScan;
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fdwroutine->AnalyzeForeignTable = fileAnalyzeForeignTable;
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fdwroutine->IsForeignScanParallelSafe = fileIsForeignScanParallelSafe;
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PG_RETURN_POINTER(fdwroutine);
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}
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/*
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* Validate the generic options given to a FOREIGN DATA WRAPPER, SERVER,
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* USER MAPPING or FOREIGN TABLE that uses file_fdw.
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*
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* Raise an ERROR if the option or its value is considered invalid.
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*/
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Datum
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file_fdw_validator(PG_FUNCTION_ARGS)
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{
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List *options_list = untransformRelOptions(PG_GETARG_DATUM(0));
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Oid catalog = PG_GETARG_OID(1);
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char *filename = NULL;
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DefElem *force_not_null = NULL;
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DefElem *force_null = NULL;
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List *other_options = NIL;
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ListCell *cell;
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/*
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* Check that only options supported by file_fdw, and allowed for the
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* current object type, are given.
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*/
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foreach(cell, options_list)
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{
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DefElem *def = (DefElem *) lfirst(cell);
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if (!is_valid_option(def->defname, catalog))
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{
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const struct FileFdwOption *opt;
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StringInfoData buf;
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/*
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* Unknown option specified, complain about it. Provide a hint
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* with list of valid options for the object.
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*/
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initStringInfo(&buf);
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for (opt = valid_options; opt->optname; opt++)
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{
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if (catalog == opt->optcontext)
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appendStringInfo(&buf, "%s%s", (buf.len > 0) ? ", " : "",
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opt->optname);
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}
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ereport(ERROR,
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(errcode(ERRCODE_FDW_INVALID_OPTION_NAME),
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errmsg("invalid option \"%s\"", def->defname),
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buf.len > 0
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? errhint("Valid options in this context are: %s",
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buf.data)
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: errhint("There are no valid options in this context.")));
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}
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/*
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* Separate out filename, program, and column-specific options, since
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* ProcessCopyOptions won't accept them.
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*/
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if (strcmp(def->defname, "filename") == 0 ||
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strcmp(def->defname, "program") == 0)
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{
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if (filename)
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ereport(ERROR,
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(errcode(ERRCODE_SYNTAX_ERROR),
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errmsg("conflicting or redundant options")));
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/*
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* Check permissions for changing which file or program is used by
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* the file_fdw.
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*
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* Only members of the role 'pg_read_server_files' are allowed to
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* set the 'filename' option of a file_fdw foreign table, while
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* only members of the role 'pg_execute_server_program' are
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* allowed to set the 'program' option. This is because we don't
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* want regular users to be able to control which file gets read
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* or which program gets executed.
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*
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* Putting this sort of permissions check in a validator is a bit
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* of a crock, but there doesn't seem to be any other place that
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* can enforce the check more cleanly.
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*
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* Note that the valid_options[] array disallows setting filename
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* and program at any options level other than foreign table ---
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* otherwise there'd still be a security hole.
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*/
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if (strcmp(def->defname, "filename") == 0 &&
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!is_member_of_role(GetUserId(), ROLE_PG_READ_SERVER_FILES))
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ereport(ERROR,
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(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
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errmsg("only superuser or a member of the pg_read_server_files role may specify the filename option of a file_fdw foreign table")));
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if (strcmp(def->defname, "program") == 0 &&
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!is_member_of_role(GetUserId(), ROLE_PG_EXECUTE_SERVER_PROGRAM))
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ereport(ERROR,
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(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
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errmsg("only superuser or a member of the pg_execute_server_program role may specify the program option of a file_fdw foreign table")));
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filename = defGetString(def);
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}
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/*
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* force_not_null is a boolean option; after validation we can discard
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* it - it will be retrieved later in get_file_fdw_attribute_options()
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*/
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else if (strcmp(def->defname, "force_not_null") == 0)
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{
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if (force_not_null)
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ereport(ERROR,
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(errcode(ERRCODE_SYNTAX_ERROR),
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errmsg("conflicting or redundant options"),
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errhint("Option \"force_not_null\" supplied more than once for a column.")));
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force_not_null = def;
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/* Don't care what the value is, as long as it's a legal boolean */
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(void) defGetBoolean(def);
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}
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/* See comments for force_not_null above */
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else if (strcmp(def->defname, "force_null") == 0)
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{
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if (force_null)
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ereport(ERROR,
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(errcode(ERRCODE_SYNTAX_ERROR),
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errmsg("conflicting or redundant options"),
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errhint("Option \"force_null\" supplied more than once for a column.")));
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force_null = def;
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(void) defGetBoolean(def);
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}
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else
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other_options = lappend(other_options, def);
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}
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/*
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* Now apply the core COPY code's validation logic for more checks.
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*/
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ProcessCopyOptions(NULL, NULL, true, other_options);
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/*
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* Either filename or program option is required for file_fdw foreign
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* tables.
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*/
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if (catalog == ForeignTableRelationId && filename == NULL)
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ereport(ERROR,
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(errcode(ERRCODE_FDW_DYNAMIC_PARAMETER_VALUE_NEEDED),
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errmsg("either filename or program is required for file_fdw foreign tables")));
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PG_RETURN_VOID();
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}
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/*
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* Check if the provided option is one of the valid options.
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* context is the Oid of the catalog holding the object the option is for.
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*/
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static bool
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is_valid_option(const char *option, Oid context)
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{
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const struct FileFdwOption *opt;
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for (opt = valid_options; opt->optname; opt++)
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{
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if (context == opt->optcontext && strcmp(opt->optname, option) == 0)
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return true;
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}
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return false;
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}
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/*
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* Fetch the options for a file_fdw foreign table.
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*
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* We have to separate out filename/program from the other options because
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* those must not appear in the options list passed to the core COPY code.
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*/
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static void
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fileGetOptions(Oid foreigntableid,
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char **filename, bool *is_program, List **other_options)
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{
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ForeignTable *table;
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ForeignServer *server;
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ForeignDataWrapper *wrapper;
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List *options;
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ListCell *lc;
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/*
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* Extract options from FDW objects. We ignore user mappings because
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* file_fdw doesn't have any options that can be specified there.
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*
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* (XXX Actually, given the current contents of valid_options[], there's
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* no point in examining anything except the foreign table's own options.
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* Simplify?)
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*/
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table = GetForeignTable(foreigntableid);
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server = GetForeignServer(table->serverid);
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wrapper = GetForeignDataWrapper(server->fdwid);
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options = NIL;
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options = list_concat(options, wrapper->options);
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options = list_concat(options, server->options);
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options = list_concat(options, table->options);
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options = list_concat(options, get_file_fdw_attribute_options(foreigntableid));
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/*
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* Separate out the filename or program option (we assume there is only
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* one).
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*/
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*filename = NULL;
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*is_program = false;
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foreach(lc, options)
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{
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DefElem *def = (DefElem *) lfirst(lc);
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if (strcmp(def->defname, "filename") == 0)
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{
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*filename = defGetString(def);
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options = foreach_delete_current(options, lc);
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break;
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}
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else if (strcmp(def->defname, "program") == 0)
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{
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*filename = defGetString(def);
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*is_program = true;
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options = foreach_delete_current(options, lc);
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break;
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}
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}
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/*
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* The validator should have checked that filename or program was included
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* in the options, but check again, just in case.
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*/
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if (*filename == NULL)
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elog(ERROR, "either filename or program is required for file_fdw foreign tables");
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*other_options = options;
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}
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/*
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* Retrieve per-column generic options from pg_attribute and construct a list
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* of DefElems representing them.
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*
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* At the moment we only have "force_not_null", and "force_null",
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* which should each be combined into a single DefElem listing all such
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* columns, since that's what COPY expects.
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*/
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static List *
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get_file_fdw_attribute_options(Oid relid)
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{
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Relation rel;
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TupleDesc tupleDesc;
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AttrNumber natts;
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AttrNumber attnum;
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List *fnncolumns = NIL;
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List *fncolumns = NIL;
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List *options = NIL;
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rel = table_open(relid, AccessShareLock);
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tupleDesc = RelationGetDescr(rel);
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natts = tupleDesc->natts;
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/* Retrieve FDW options for all user-defined attributes. */
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for (attnum = 1; attnum <= natts; attnum++)
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{
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Form_pg_attribute attr = TupleDescAttr(tupleDesc, attnum - 1);
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List *options;
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ListCell *lc;
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|
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/* Skip dropped attributes. */
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if (attr->attisdropped)
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continue;
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options = GetForeignColumnOptions(relid, attnum);
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foreach(lc, options)
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{
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DefElem *def = (DefElem *) lfirst(lc);
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if (strcmp(def->defname, "force_not_null") == 0)
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{
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if (defGetBoolean(def))
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{
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char *attname = pstrdup(NameStr(attr->attname));
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fnncolumns = lappend(fnncolumns, makeString(attname));
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}
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}
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else if (strcmp(def->defname, "force_null") == 0)
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{
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if (defGetBoolean(def))
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{
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char *attname = pstrdup(NameStr(attr->attname));
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fncolumns = lappend(fncolumns, makeString(attname));
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}
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}
|
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/* maybe in future handle other options here */
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}
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}
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|
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table_close(rel, AccessShareLock);
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|
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/*
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* Return DefElem only when some column(s) have force_not_null /
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* force_null options set
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*/
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if (fnncolumns != NIL)
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options = lappend(options, makeDefElem("force_not_null", (Node *) fnncolumns, -1));
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if (fncolumns != NIL)
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options = lappend(options, makeDefElem("force_null", (Node *) fncolumns, -1));
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|
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return options;
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}
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|
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/*
|
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* fileGetForeignRelSize
|
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* Obtain relation size estimates for a foreign table
|
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*/
|
|
static void
|
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fileGetForeignRelSize(PlannerInfo *root,
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RelOptInfo *baserel,
|
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Oid foreigntableid)
|
|
{
|
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FileFdwPlanState *fdw_private;
|
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|
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/*
|
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* Fetch options. We only need filename (or program) at this point, but
|
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* we might as well get everything and not need to re-fetch it later in
|
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* planning.
|
|
*/
|
|
fdw_private = (FileFdwPlanState *) palloc(sizeof(FileFdwPlanState));
|
|
fileGetOptions(foreigntableid,
|
|
&fdw_private->filename,
|
|
&fdw_private->is_program,
|
|
&fdw_private->options);
|
|
baserel->fdw_private = (void *) fdw_private;
|
|
|
|
/* Estimate relation size */
|
|
estimate_size(root, baserel, fdw_private);
|
|
}
|
|
|
|
/*
|
|
* fileGetForeignPaths
|
|
* Create possible access paths for a scan on the foreign table
|
|
*
|
|
* Currently we don't support any push-down feature, so there is only one
|
|
* possible access path, which simply returns all records in the order in
|
|
* the data file.
|
|
*/
|
|
static void
|
|
fileGetForeignPaths(PlannerInfo *root,
|
|
RelOptInfo *baserel,
|
|
Oid foreigntableid)
|
|
{
|
|
FileFdwPlanState *fdw_private = (FileFdwPlanState *) baserel->fdw_private;
|
|
Cost startup_cost;
|
|
Cost total_cost;
|
|
List *columns;
|
|
List *coptions = NIL;
|
|
|
|
/* Decide whether to selectively perform binary conversion */
|
|
if (check_selective_binary_conversion(baserel,
|
|
foreigntableid,
|
|
&columns))
|
|
coptions = list_make1(makeDefElem("convert_selectively",
|
|
(Node *) columns, -1));
|
|
|
|
/* Estimate costs */
|
|
estimate_costs(root, baserel, fdw_private,
|
|
&startup_cost, &total_cost);
|
|
|
|
/*
|
|
* Create a ForeignPath node and add it as only possible path. We use the
|
|
* fdw_private list of the path to carry the convert_selectively option;
|
|
* it will be propagated into the fdw_private list of the Plan node.
|
|
*
|
|
* We don't support pushing join clauses into the quals of this path, but
|
|
* it could still have required parameterization due to LATERAL refs in
|
|
* its tlist.
|
|
*/
|
|
add_path(baserel, (Path *)
|
|
create_foreignscan_path(root, baserel,
|
|
NULL, /* default pathtarget */
|
|
baserel->rows,
|
|
startup_cost,
|
|
total_cost,
|
|
NIL, /* no pathkeys */
|
|
baserel->lateral_relids,
|
|
NULL, /* no extra plan */
|
|
coptions));
|
|
|
|
/*
|
|
* If data file was sorted, and we knew it somehow, we could insert
|
|
* appropriate pathkeys into the ForeignPath node to tell the planner
|
|
* that.
|
|
*/
|
|
}
|
|
|
|
/*
|
|
* fileGetForeignPlan
|
|
* Create a ForeignScan plan node for scanning the foreign table
|
|
*/
|
|
static ForeignScan *
|
|
fileGetForeignPlan(PlannerInfo *root,
|
|
RelOptInfo *baserel,
|
|
Oid foreigntableid,
|
|
ForeignPath *best_path,
|
|
List *tlist,
|
|
List *scan_clauses,
|
|
Plan *outer_plan)
|
|
{
|
|
Index scan_relid = baserel->relid;
|
|
|
|
/*
|
|
* We have no native ability to evaluate restriction clauses, so we just
|
|
* put all the scan_clauses into the plan node's qual list for the
|
|
* executor to check. So all we have to do here is strip RestrictInfo
|
|
* nodes from the clauses and ignore pseudoconstants (which will be
|
|
* handled elsewhere).
|
|
*/
|
|
scan_clauses = extract_actual_clauses(scan_clauses, false);
|
|
|
|
/* Create the ForeignScan node */
|
|
return make_foreignscan(tlist,
|
|
scan_clauses,
|
|
scan_relid,
|
|
NIL, /* no expressions to evaluate */
|
|
best_path->fdw_private,
|
|
NIL, /* no custom tlist */
|
|
NIL, /* no remote quals */
|
|
outer_plan);
|
|
}
|
|
|
|
/*
|
|
* fileExplainForeignScan
|
|
* Produce extra output for EXPLAIN
|
|
*/
|
|
static void
|
|
fileExplainForeignScan(ForeignScanState *node, ExplainState *es)
|
|
{
|
|
char *filename;
|
|
bool is_program;
|
|
List *options;
|
|
|
|
/* Fetch options --- we only need filename and is_program at this point */
|
|
fileGetOptions(RelationGetRelid(node->ss.ss_currentRelation),
|
|
&filename, &is_program, &options);
|
|
|
|
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 (!is_program &&
|
|
stat(filename, &stat_buf) == 0)
|
|
ExplainPropertyInteger("Foreign File Size", "b",
|
|
(int64) stat_buf.st_size, es);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* fileBeginForeignScan
|
|
* Initiate access to the file by creating CopyState
|
|
*/
|
|
static void
|
|
fileBeginForeignScan(ForeignScanState *node, int eflags)
|
|
{
|
|
ForeignScan *plan = (ForeignScan *) node->ss.ps.plan;
|
|
char *filename;
|
|
bool is_program;
|
|
List *options;
|
|
CopyFromState cstate;
|
|
FileFdwExecutionState *festate;
|
|
|
|
/*
|
|
* Do nothing in EXPLAIN (no ANALYZE) case. node->fdw_state stays NULL.
|
|
*/
|
|
if (eflags & EXEC_FLAG_EXPLAIN_ONLY)
|
|
return;
|
|
|
|
/* Fetch options of foreign table */
|
|
fileGetOptions(RelationGetRelid(node->ss.ss_currentRelation),
|
|
&filename, &is_program, &options);
|
|
|
|
/* Add any options from the plan (currently only convert_selectively) */
|
|
options = list_concat(options, plan->fdw_private);
|
|
|
|
/*
|
|
* Create CopyState from FDW options. We always acquire all columns, so
|
|
* as to match the expected ScanTupleSlot signature.
|
|
*/
|
|
cstate = BeginCopyFrom(NULL,
|
|
node->ss.ss_currentRelation,
|
|
NULL,
|
|
filename,
|
|
is_program,
|
|
NULL,
|
|
NIL,
|
|
options);
|
|
|
|
/*
|
|
* Save state in node->fdw_state. We must save enough information to call
|
|
* BeginCopyFrom() again.
|
|
*/
|
|
festate = (FileFdwExecutionState *) palloc(sizeof(FileFdwExecutionState));
|
|
festate->filename = filename;
|
|
festate->is_program = is_program;
|
|
festate->options = options;
|
|
festate->cstate = cstate;
|
|
|
|
node->fdw_state = (void *) festate;
|
|
}
|
|
|
|
/*
|
|
* fileIterateForeignScan
|
|
* Read next record from the data file and store it into the
|
|
* ScanTupleSlot as a virtual tuple
|
|
*/
|
|
static TupleTableSlot *
|
|
fileIterateForeignScan(ForeignScanState *node)
|
|
{
|
|
FileFdwExecutionState *festate = (FileFdwExecutionState *) node->fdw_state;
|
|
TupleTableSlot *slot = node->ss.ss_ScanTupleSlot;
|
|
bool found;
|
|
ErrorContextCallback errcallback;
|
|
|
|
/* Set up callback to identify error line number. */
|
|
errcallback.callback = CopyFromErrorCallback;
|
|
errcallback.arg = (void *) festate->cstate;
|
|
errcallback.previous = error_context_stack;
|
|
error_context_stack = &errcallback;
|
|
|
|
/*
|
|
* The protocol for loading a virtual tuple into a slot is first
|
|
* ExecClearTuple, then fill the values/isnull arrays, then
|
|
* ExecStoreVirtualTuple. If we don't find another row in the file, we
|
|
* just skip the last step, leaving the slot empty as required.
|
|
*
|
|
* We can pass ExprContext = NULL because we read all columns from the
|
|
* file, so no need to evaluate default expressions.
|
|
*/
|
|
ExecClearTuple(slot);
|
|
found = NextCopyFrom(festate->cstate, NULL,
|
|
slot->tts_values, slot->tts_isnull);
|
|
if (found)
|
|
ExecStoreVirtualTuple(slot);
|
|
|
|
/* Remove error callback. */
|
|
error_context_stack = errcallback.previous;
|
|
|
|
return slot;
|
|
}
|
|
|
|
/*
|
|
* fileReScanForeignScan
|
|
* Rescan table, possibly with new parameters
|
|
*/
|
|
static void
|
|
fileReScanForeignScan(ForeignScanState *node)
|
|
{
|
|
FileFdwExecutionState *festate = (FileFdwExecutionState *) node->fdw_state;
|
|
|
|
EndCopyFrom(festate->cstate);
|
|
|
|
festate->cstate = BeginCopyFrom(NULL,
|
|
node->ss.ss_currentRelation,
|
|
NULL,
|
|
festate->filename,
|
|
festate->is_program,
|
|
NULL,
|
|
NIL,
|
|
festate->options);
|
|
}
|
|
|
|
/*
|
|
* fileEndForeignScan
|
|
* Finish scanning foreign table and dispose objects used for this scan
|
|
*/
|
|
static void
|
|
fileEndForeignScan(ForeignScanState *node)
|
|
{
|
|
FileFdwExecutionState *festate = (FileFdwExecutionState *) node->fdw_state;
|
|
|
|
/* if festate is NULL, we are in EXPLAIN; nothing to do */
|
|
if (festate)
|
|
EndCopyFrom(festate->cstate);
|
|
}
|
|
|
|
/*
|
|
* fileAnalyzeForeignTable
|
|
* Test whether analyzing this foreign table is supported
|
|
*/
|
|
static bool
|
|
fileAnalyzeForeignTable(Relation relation,
|
|
AcquireSampleRowsFunc *func,
|
|
BlockNumber *totalpages)
|
|
{
|
|
char *filename;
|
|
bool is_program;
|
|
List *options;
|
|
struct stat stat_buf;
|
|
|
|
/* Fetch options of foreign table */
|
|
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
|
|
* return false to skip analyzing the table?)
|
|
*/
|
|
if (stat(filename, &stat_buf) < 0)
|
|
ereport(ERROR,
|
|
(errcode_for_file_access(),
|
|
errmsg("could not stat file \"%s\": %m",
|
|
filename)));
|
|
|
|
/*
|
|
* Convert size to pages. Must return at least 1 so that we can tell
|
|
* later on that pg_class.relpages is not default.
|
|
*/
|
|
*totalpages = (stat_buf.st_size + (BLCKSZ - 1)) / BLCKSZ;
|
|
if (*totalpages < 1)
|
|
*totalpages = 1;
|
|
|
|
*func = file_acquire_sample_rows;
|
|
|
|
return true;
|
|
}
|
|
|
|
/*
|
|
* fileIsForeignScanParallelSafe
|
|
* 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,
|
|
RangeTblEntry *rte)
|
|
{
|
|
return true;
|
|
}
|
|
|
|
/*
|
|
* check_selective_binary_conversion
|
|
*
|
|
* Check to see if it's useful to convert only a subset of the file's columns
|
|
* to binary. If so, construct a list of the column names to be converted,
|
|
* return that at *columns, and return true. (Note that it's possible to
|
|
* determine that no columns need be converted, for instance with a COUNT(*)
|
|
* query. So we can't use returning a NIL list to indicate failure.)
|
|
*/
|
|
static bool
|
|
check_selective_binary_conversion(RelOptInfo *baserel,
|
|
Oid foreigntableid,
|
|
List **columns)
|
|
{
|
|
ForeignTable *table;
|
|
ListCell *lc;
|
|
Relation rel;
|
|
TupleDesc tupleDesc;
|
|
AttrNumber attnum;
|
|
Bitmapset *attrs_used = NULL;
|
|
bool has_wholerow = false;
|
|
int numattrs;
|
|
int i;
|
|
|
|
*columns = NIL; /* default result */
|
|
|
|
/*
|
|
* Check format of the file. If binary format, this is irrelevant.
|
|
*/
|
|
table = GetForeignTable(foreigntableid);
|
|
foreach(lc, table->options)
|
|
{
|
|
DefElem *def = (DefElem *) lfirst(lc);
|
|
|
|
if (strcmp(def->defname, "format") == 0)
|
|
{
|
|
char *format = defGetString(def);
|
|
|
|
if (strcmp(format, "binary") == 0)
|
|
return false;
|
|
break;
|
|
}
|
|
}
|
|
|
|
/* Collect all the attributes needed for joins or final output. */
|
|
pull_varattnos((Node *) baserel->reltarget->exprs, baserel->relid,
|
|
&attrs_used);
|
|
|
|
/* Add all the attributes used by restriction clauses. */
|
|
foreach(lc, baserel->baserestrictinfo)
|
|
{
|
|
RestrictInfo *rinfo = (RestrictInfo *) lfirst(lc);
|
|
|
|
pull_varattnos((Node *) rinfo->clause, baserel->relid,
|
|
&attrs_used);
|
|
}
|
|
|
|
/* Convert attribute numbers to column names. */
|
|
rel = table_open(foreigntableid, AccessShareLock);
|
|
tupleDesc = RelationGetDescr(rel);
|
|
|
|
while ((attnum = bms_first_member(attrs_used)) >= 0)
|
|
{
|
|
/* Adjust for system attributes. */
|
|
attnum += FirstLowInvalidHeapAttributeNumber;
|
|
|
|
if (attnum == 0)
|
|
{
|
|
has_wholerow = true;
|
|
break;
|
|
}
|
|
|
|
/* Ignore system attributes. */
|
|
if (attnum < 0)
|
|
continue;
|
|
|
|
/* Get user attributes. */
|
|
if (attnum > 0)
|
|
{
|
|
Form_pg_attribute attr = TupleDescAttr(tupleDesc, attnum - 1);
|
|
char *attname = NameStr(attr->attname);
|
|
|
|
/* Skip dropped attributes (probably shouldn't see any here). */
|
|
if (attr->attisdropped)
|
|
continue;
|
|
|
|
/*
|
|
* Skip generated columns (COPY won't accept them in the column
|
|
* list)
|
|
*/
|
|
if (attr->attgenerated)
|
|
continue;
|
|
*columns = lappend(*columns, makeString(pstrdup(attname)));
|
|
}
|
|
}
|
|
|
|
/* Count non-dropped user attributes while we have the tupdesc. */
|
|
numattrs = 0;
|
|
for (i = 0; i < tupleDesc->natts; i++)
|
|
{
|
|
Form_pg_attribute attr = TupleDescAttr(tupleDesc, i);
|
|
|
|
if (attr->attisdropped)
|
|
continue;
|
|
numattrs++;
|
|
}
|
|
|
|
table_close(rel, AccessShareLock);
|
|
|
|
/* If there's a whole-row reference, fail: we need all the columns. */
|
|
if (has_wholerow)
|
|
{
|
|
*columns = NIL;
|
|
return false;
|
|
}
|
|
|
|
/* If all the user attributes are needed, fail. */
|
|
if (numattrs == list_length(*columns))
|
|
{
|
|
*columns = NIL;
|
|
return false;
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
/*
|
|
* Estimate size of a foreign table.
|
|
*
|
|
* The main result is returned in baserel->rows. We also set
|
|
* fdw_private->pages and fdw_private->ntuples for later use in the cost
|
|
* calculation.
|
|
*/
|
|
static void
|
|
estimate_size(PlannerInfo *root, RelOptInfo *baserel,
|
|
FileFdwPlanState *fdw_private)
|
|
{
|
|
struct stat stat_buf;
|
|
BlockNumber pages;
|
|
double ntuples;
|
|
double nrows;
|
|
|
|
/*
|
|
* Get size of the file. It might not be there at plan time, though, in
|
|
* 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 (fdw_private->is_program || stat(fdw_private->filename, &stat_buf) < 0)
|
|
stat_buf.st_size = 10 * BLCKSZ;
|
|
|
|
/*
|
|
* Convert size to pages for use in I/O cost estimate later.
|
|
*/
|
|
pages = (stat_buf.st_size + (BLCKSZ - 1)) / BLCKSZ;
|
|
if (pages < 1)
|
|
pages = 1;
|
|
fdw_private->pages = pages;
|
|
|
|
/*
|
|
* Estimate the number of tuples in the file.
|
|
*/
|
|
if (baserel->tuples >= 0 && baserel->pages > 0)
|
|
{
|
|
/*
|
|
* We have # of pages and # of tuples from pg_class (that is, from a
|
|
* previous ANALYZE), so compute a tuples-per-page estimate and scale
|
|
* that by the current file size.
|
|
*/
|
|
double density;
|
|
|
|
density = baserel->tuples / (double) baserel->pages;
|
|
ntuples = clamp_row_est(density * (double) pages);
|
|
}
|
|
else
|
|
{
|
|
/*
|
|
* Otherwise we have to fake it. We back into this estimate using the
|
|
* planner's idea of the relation width; which is bogus if not all
|
|
* columns are being read, not to mention that the text representation
|
|
* of a row probably isn't the same size as its internal
|
|
* representation. Possibly we could do something better, but the
|
|
* real answer to anyone who complains is "ANALYZE" ...
|
|
*/
|
|
int tuple_width;
|
|
|
|
tuple_width = MAXALIGN(baserel->reltarget->width) +
|
|
MAXALIGN(SizeofHeapTupleHeader);
|
|
ntuples = clamp_row_est((double) stat_buf.st_size /
|
|
(double) tuple_width);
|
|
}
|
|
fdw_private->ntuples = ntuples;
|
|
|
|
/*
|
|
* Now estimate the number of rows returned by the scan after applying the
|
|
* baserestrictinfo quals.
|
|
*/
|
|
nrows = ntuples *
|
|
clauselist_selectivity(root,
|
|
baserel->baserestrictinfo,
|
|
0,
|
|
JOIN_INNER,
|
|
NULL);
|
|
|
|
nrows = clamp_row_est(nrows);
|
|
|
|
/* Save the output-rows estimate for the planner */
|
|
baserel->rows = nrows;
|
|
}
|
|
|
|
/*
|
|
* Estimate costs of scanning a foreign table.
|
|
*
|
|
* Results are returned in *startup_cost and *total_cost.
|
|
*/
|
|
static void
|
|
estimate_costs(PlannerInfo *root, RelOptInfo *baserel,
|
|
FileFdwPlanState *fdw_private,
|
|
Cost *startup_cost, Cost *total_cost)
|
|
{
|
|
BlockNumber pages = fdw_private->pages;
|
|
double ntuples = fdw_private->ntuples;
|
|
Cost run_cost = 0;
|
|
Cost cpu_per_tuple;
|
|
|
|
/*
|
|
* We estimate costs almost the same way as cost_seqscan(), thus assuming
|
|
* 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;
|
|
|
|
*startup_cost = baserel->baserestrictcost.startup;
|
|
cpu_per_tuple = cpu_tuple_cost * 10 + baserel->baserestrictcost.per_tuple;
|
|
run_cost += cpu_per_tuple * ntuples;
|
|
*total_cost = *startup_cost + run_cost;
|
|
}
|
|
|
|
/*
|
|
* file_acquire_sample_rows -- acquire a random sample of rows from the table
|
|
*
|
|
* Selected rows are returned in the caller-allocated array rows[],
|
|
* which must have at least targrows entries.
|
|
* The actual number of rows selected is returned as the function result.
|
|
* We also count the total number of rows in the file and return it into
|
|
* *totalrows. Note that *totaldeadrows is always set to 0.
|
|
*
|
|
* Note that the returned list of rows is not always in order by physical
|
|
* position in the file. Therefore, correlation estimates derived later
|
|
* may be meaningless, but it's OK because we don't use the estimates
|
|
* currently (the planner only pays attention to correlation for indexscans).
|
|
*/
|
|
static int
|
|
file_acquire_sample_rows(Relation onerel, int elevel,
|
|
HeapTuple *rows, int targrows,
|
|
double *totalrows, double *totaldeadrows)
|
|
{
|
|
int numrows = 0;
|
|
double rowstoskip = -1; /* -1 means not set yet */
|
|
ReservoirStateData rstate;
|
|
TupleDesc tupDesc;
|
|
Datum *values;
|
|
bool *nulls;
|
|
bool found;
|
|
char *filename;
|
|
bool is_program;
|
|
List *options;
|
|
CopyFromState cstate;
|
|
ErrorContextCallback errcallback;
|
|
MemoryContext oldcontext = CurrentMemoryContext;
|
|
MemoryContext tupcontext;
|
|
|
|
Assert(onerel);
|
|
Assert(targrows > 0);
|
|
|
|
tupDesc = RelationGetDescr(onerel);
|
|
values = (Datum *) palloc(tupDesc->natts * sizeof(Datum));
|
|
nulls = (bool *) palloc(tupDesc->natts * sizeof(bool));
|
|
|
|
/* Fetch options of foreign table */
|
|
fileGetOptions(RelationGetRelid(onerel), &filename, &is_program, &options);
|
|
|
|
/*
|
|
* Create CopyState from FDW options.
|
|
*/
|
|
cstate = BeginCopyFrom(NULL, onerel, NULL, filename, is_program, NULL, NIL,
|
|
options);
|
|
|
|
/*
|
|
* Use per-tuple memory context to prevent leak of memory used to read
|
|
* rows from the file with Copy routines.
|
|
*/
|
|
tupcontext = AllocSetContextCreate(CurrentMemoryContext,
|
|
"file_fdw temporary context",
|
|
ALLOCSET_DEFAULT_SIZES);
|
|
|
|
/* Prepare for sampling rows */
|
|
reservoir_init_selection_state(&rstate, targrows);
|
|
|
|
/* Set up callback to identify error line number. */
|
|
errcallback.callback = CopyFromErrorCallback;
|
|
errcallback.arg = (void *) cstate;
|
|
errcallback.previous = error_context_stack;
|
|
error_context_stack = &errcallback;
|
|
|
|
*totalrows = 0;
|
|
*totaldeadrows = 0;
|
|
for (;;)
|
|
{
|
|
/* Check for user-requested abort or sleep */
|
|
vacuum_delay_point();
|
|
|
|
/* Fetch next row */
|
|
MemoryContextReset(tupcontext);
|
|
MemoryContextSwitchTo(tupcontext);
|
|
|
|
found = NextCopyFrom(cstate, NULL, values, nulls);
|
|
|
|
MemoryContextSwitchTo(oldcontext);
|
|
|
|
if (!found)
|
|
break;
|
|
|
|
/*
|
|
* The first targrows sample rows are simply copied into the
|
|
* reservoir. Then we start replacing tuples in the sample until we
|
|
* reach the end of the relation. This algorithm is from Jeff Vitter's
|
|
* paper (see more info in commands/analyze.c).
|
|
*/
|
|
if (numrows < targrows)
|
|
{
|
|
rows[numrows++] = heap_form_tuple(tupDesc, values, nulls);
|
|
}
|
|
else
|
|
{
|
|
/*
|
|
* t in Vitter's paper is the number of records already processed.
|
|
* If we need to compute a new S value, we must use the
|
|
* not-yet-incremented value of totalrows as t.
|
|
*/
|
|
if (rowstoskip < 0)
|
|
rowstoskip = reservoir_get_next_S(&rstate, *totalrows, targrows);
|
|
|
|
if (rowstoskip <= 0)
|
|
{
|
|
/*
|
|
* Found a suitable tuple, so save it, replacing one old tuple
|
|
* at random
|
|
*/
|
|
int k = (int) (targrows * sampler_random_fract(rstate.randstate));
|
|
|
|
Assert(k >= 0 && k < targrows);
|
|
heap_freetuple(rows[k]);
|
|
rows[k] = heap_form_tuple(tupDesc, values, nulls);
|
|
}
|
|
|
|
rowstoskip -= 1;
|
|
}
|
|
|
|
*totalrows += 1;
|
|
}
|
|
|
|
/* Remove error callback. */
|
|
error_context_stack = errcallback.previous;
|
|
|
|
/* Clean up. */
|
|
MemoryContextDelete(tupcontext);
|
|
|
|
EndCopyFrom(cstate);
|
|
|
|
pfree(values);
|
|
pfree(nulls);
|
|
|
|
/*
|
|
* Emit some interesting relation info
|
|
*/
|
|
ereport(elevel,
|
|
(errmsg("\"%s\": file contains %.0f rows; "
|
|
"%d rows in sample",
|
|
RelationGetRelationName(onerel),
|
|
*totalrows, numrows)));
|
|
|
|
return numrows;
|
|
}
|