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1204 lines
33 KiB
C
1204 lines
33 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) 2010-2018, 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 "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/cost.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 "optimizer/var.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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CopyState 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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* Only superusers are allowed to set options of a file_fdw foreign table.
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* This is because we don't want non-superusers to be able to control
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* which file gets read 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 of a
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* crock, but there doesn't seem to be any other place that can enforce
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* the check more cleanly.
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*
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* Note that the valid_options[] array disallows setting filename and
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* program at any options level other than foreign table --- otherwise
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* there'd still be a security hole.
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*/
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if (catalog == ForeignTableRelationId && !superuser())
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ereport(ERROR,
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(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
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errmsg("only superuser can change options of a file_fdw foreign table")));
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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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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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*prev;
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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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prev = NULL;
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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 = list_delete_cell(options, lc, prev);
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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 = list_delete_cell(options, lc, prev);
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break;
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}
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prev = lc;
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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 = heap_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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/* 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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heap_close(rel, AccessShareLock);
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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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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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*/
|
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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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{
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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.
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*/
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fdw_private = (FileFdwPlanState *) palloc(sizeof(FileFdwPlanState));
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fileGetOptions(foreigntableid,
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&fdw_private->filename,
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&fdw_private->is_program,
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&fdw_private->options);
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baserel->fdw_private = (void *) fdw_private;
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/* Estimate relation size */
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estimate_size(root, baserel, fdw_private);
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}
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|
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/*
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* fileGetForeignPaths
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* Create possible access paths for a scan on the foreign table
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*
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* Currently we don't support any push-down feature, so there is only one
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* possible access path, which simply returns all records in the order in
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* the data file.
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*/
|
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static void
|
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fileGetForeignPaths(PlannerInfo *root,
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RelOptInfo *baserel,
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Oid foreigntableid)
|
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{
|
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FileFdwPlanState *fdw_private = (FileFdwPlanState *) baserel->fdw_private;
|
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Cost startup_cost;
|
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Cost total_cost;
|
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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.
|
|
*/
|
|
add_path(baserel, (Path *)
|
|
create_foreignscan_path(root, baserel,
|
|
NULL, /* default pathtarget */
|
|
baserel->rows,
|
|
startup_cost,
|
|
total_cost,
|
|
NIL, /* no pathkeys */
|
|
NULL, /* no outer rel either */
|
|
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)
|
|
ExplainPropertyLong("Foreign File Size", (long) 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;
|
|
CopyState 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,
|
|
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.
|
|
*
|
|
* We can also pass tupleOid = NULL because we don't allow oids for
|
|
* foreign tables.
|
|
*/
|
|
ExecClearTuple(slot);
|
|
found = NextCopyFrom(festate->cstate, NULL,
|
|
slot->tts_values, slot->tts_isnull,
|
|
NULL);
|
|
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,
|
|
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 = heap_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;
|
|
*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++;
|
|
}
|
|
|
|
heap_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->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;
|
|
CopyState 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, 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, NULL);
|
|
|
|
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;
|
|
}
|