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influxdb_fdw.c
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influxdb_fdw.c
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/*-------------------------------------------------------------------------
*
* InfluxDB Foreign Data Wrapper for PostgreSQL
*
* Portions Copyright (c) 2018, TOSHIBA CORPORATION
*
* IDENTIFICATION
* influxdb_fdw.c
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "influxdb_fdw.h"
#include <stdio.h>
#include "access/reloptions.h"
#include "access/htup_details.h"
#include "access/sysattr.h"
#include "foreign/fdwapi.h"
#include "foreign/foreign.h"
#if (PG_VERSION_NUM >= 140000)
#include "optimizer/appendinfo.h"
#endif
#include "optimizer/pathnode.h"
#include "optimizer/planmain.h"
#include "optimizer/cost.h"
#include "optimizer/clauses.h"
#include "optimizer/restrictinfo.h"
#include "optimizer/paths.h"
#include "optimizer/prep.h"
#include "optimizer/restrictinfo.h"
#include "optimizer/tlist.h"
#include "funcapi.h"
#include "utils/builtins.h"
#include "utils/formatting.h"
#include "utils/rel.h"
#include "utils/lsyscache.h"
#include "utils/array.h"
#include "utils/date.h"
#include "utils/hsearch.h"
#include "utils/timestamp.h"
#include "utils/guc.h"
#include "utils/memutils.h"
#include "catalog/pg_collation.h"
#include "catalog/pg_foreign_server.h"
#include "catalog/pg_foreign_table.h"
#include "catalog/pg_user_mapping.h"
#include "catalog/pg_aggregate.h"
#include "catalog/pg_type.h"
#include "catalog/pg_proc.h"
#include "commands/defrem.h"
#include "commands/explain.h"
#include "commands/vacuum.h"
#include "storage/ipc.h"
#include "storage/latch.h"
#include "miscadmin.h"
#include "nodes/makefuncs.h"
#include "nodes/nodeFuncs.h"
#include "parser/parsetree.h"
#include "utils/typcache.h"
#include "utils/selfuncs.h"
#include "utils/syscache.h"
#ifdef CXX_CLIENT
#include "query_cxx.h"
#endif
extern PGDLLEXPORT void _PG_init(void);
bool influxdb_load_library(void);
static void influxdb_fdw_exit(int code, Datum arg);
PG_MODULE_MAGIC;
/* Default CPU cost to start up a foreign query. */
#define DEFAULT_FDW_STARTUP_COST 100.0
/* Default CPU cost to process 1 row (above and beyond cpu_tuple_cost). */
#define DEFAULT_FDW_TUPLE_COST 0.01
/* If no remote estimates, assume a sort costs 20% extra */
#define DEFAULT_FDW_SORT_MULTIPLIER 1.2
#define IS_KEY_COLUMN(A) ((strcmp(A->defname, "key") == 0) && \
(strcmp(((Value *)(A->arg))->val.str, "true") == 0))
#define SPD_CMD_CREATE 0
#define SPD_CMD_DROP 1
extern Datum influxdb_fdw_handler(PG_FUNCTION_ARGS);
extern Datum influxdb_fdw_validator(PG_FUNCTION_ARGS);
PG_FUNCTION_INFO_V1(influxdb_fdw_handler);
PG_FUNCTION_INFO_V1(influxdb_fdw_version);
static void influxdbGetForeignRelSize(PlannerInfo *root,
RelOptInfo *baserel,
Oid foreigntableid);
static void influxdbGetForeignPaths(PlannerInfo *root,
RelOptInfo *baserel,
Oid foreigntableid);
static ForeignScan *influxdbGetForeignPlan(PlannerInfo *root,
RelOptInfo *baserel,
Oid foreigntableid,
ForeignPath *best_path,
List *tlist,
List *scan_clauses,
Plan *outer_plan);
static void influxdbBeginForeignScan(ForeignScanState *node,
int eflags);
static TupleTableSlot *influxdbIterateForeignScan(ForeignScanState *node);
static void influxdbReScanForeignScan(ForeignScanState *node);
static void influxdbEndForeignScan(ForeignScanState *node);
static void influxdbAddForeignUpdateTargets(
#if (PG_VERSION_NUM < 140000)
Query *parsetree,
#else
PlannerInfo *root,
Index rtindex,
#endif
RangeTblEntry *target_rte,
Relation target_relation);
static List *influxdbPlanForeignModify(PlannerInfo *root,
ModifyTable *plan,
Index resultRelation,
int subplan_index);
static void influxdbBeginForeignModify(ModifyTableState *mtstate,
ResultRelInfo *resultRelInfo,
List *fdw_private,
int subplan_index,
int eflags);
static TupleTableSlot *influxdbExecForeignInsert(EState *estate,
ResultRelInfo *resultRelInfo,
TupleTableSlot *slot,
TupleTableSlot *planSlot);
#if (PG_VERSION_NUM >= 140000)
static TupleTableSlot **influxdbExecForeignBatchInsert(EState *estate,
ResultRelInfo *resultRelInfo,
TupleTableSlot **slots,
TupleTableSlot **planSlots,
int *numSlots);
static int influxdbGetForeignModifyBatchSize(ResultRelInfo *resultRelInfo);
#endif
static TupleTableSlot *influxdbExecForeignDelete(EState *estate,
ResultRelInfo *rinfo,
TupleTableSlot *slot,
TupleTableSlot *planSlot);
static void influxdbEndForeignModify(EState *estate,
ResultRelInfo *resultRelInfo);
#if (PG_VERSION_NUM >= 110000)
static void influxdbEndForeignInsert(EState *estate,
ResultRelInfo *resultRelInfo);
static void influxdbBeginForeignInsert(ModifyTableState *mtstate,
ResultRelInfo *resultRelInfo);
#endif
static bool influxdbPlanDirectModify(PlannerInfo *root,
ModifyTable *plan,
Index resultRelation,
int subplan_index);
static void influxdbBeginDirectModify(ForeignScanState *node, int eflags);
static TupleTableSlot *influxdbIterateDirectModify(ForeignScanState *node);
static void influxdbEndDirectModify(ForeignScanState *node);
static void influxdbExplainForeignScan(ForeignScanState *node,
struct ExplainState *es);
static void influxdbExplainForeignModify(ModifyTableState *mtstate,
ResultRelInfo *rinfo,
List *fdw_private,
int subplan_index,
struct ExplainState *es);
static void influxdbExplainDirectModify(ForeignScanState *node,
struct ExplainState *es);
static bool influxdbAnalyzeForeignTable(Relation relation,
AcquireSampleRowsFunc *func,
BlockNumber *totalpages);
static List *influxdbImportForeignSchema(ImportForeignSchemaStmt *stmt,
Oid serverOid);
static void influxdbGetForeignUpperPaths(PlannerInfo *root,
UpperRelationKind stage,
RelOptInfo *input_rel,
RelOptInfo *output_rel
#if (PG_VERSION_NUM >= 110000)
,void *extra
#endif
);
static void influxdb_to_pg_type(StringInfo str, char *typname);
static void prepare_query_params(PlanState *node,
List *fdw_exprs,
List *remote_exprs,
Oid foreigntableid,
int numParams,
FmgrInfo **param_flinfo,
List **param_exprs,
const char ***param_values,
Oid **param_types,
InfluxDBType * *param_influxdb_types,
InfluxDBValue * *param_influxdb_values,
InfluxDBColumnInfo * *param_column_info);
static void process_query_params(ExprContext *econtext,
FmgrInfo *param_flinfo,
List *param_exprs,
const char **param_values,
Oid *param_types,
InfluxDBType * param_influxdb_types,
InfluxDBValue * param_influxdb_values,
InfluxDBColumnInfo *param_column_info);
static void create_cursor(ForeignScanState *node);
static void execute_dml_stmt(ForeignScanState *node);
static TupleTableSlot **execute_foreign_insert_modify(EState *estate,
ResultRelInfo *resultRelInfo,
TupleTableSlot **slots,
TupleTableSlot **planSlots,
int numSlots);
static bool foreign_grouping_ok(PlannerInfo *root, RelOptInfo *grouped_rel);
static void add_foreign_grouping_paths(PlannerInfo *root,
RelOptInfo *input_rel,
RelOptInfo *grouped_rel);
static bool influxdb_contain_regex_star_functions_walker(Node *node, void *context);
static bool influxdb_contain_regex_star_functions(Node *clause);
#if (PG_VERSION_NUM >= 140000)
static int influxdb_get_batch_size_option(Relation rel);
#endif
static void influxdb_extract_slcols(InfluxDBFdwRelationInfo *fpinfo, PlannerInfo *root, RelOptInfo *baserel, List *tlist);
static bool influxdb_is_existed_measurement(Oid serverOid, char* tbl_name, influxdb_opt *options);
static bool influxdb_param_belong_to_qual(Node *qual, Node *param);
#ifdef CXX_CLIENT
#define free(x) pfree(x)
#endif
/*
* This enum describes what's kept in the fdw_private list for a ForeignPath.
* We store:
*
* 1) Boolean flag showing if the remote query has the final sort
* 2) Boolean flag showing if the remote query has the LIMIT clause
*/
enum FdwPathPrivateIndex
{
/* has-final-sort flag (as a Boolean node) */
FdwPathPrivateHasFinalSort,
/* has-limit flag (as a Boolean node) */
FdwPathPrivateHasLimit
};
/*
* Similarly, this enum describes what's kept in the fdw_private list for
* a ModifyTable node referencing a influxdb_fdw foreign table. We store:
*
* 1) DELETE statement text to be sent to the remote server
* 2) Integer list of target attribute numbers for INSERT (NIL for a DELETE)
*/
enum FdwModifyPrivateIndex
{
/* SQL statement to execute remotely (as a String node) */
FdwModifyPrivateUpdateSql,
/* Integer list of target attribute numbers */
FdwModifyPrivateTargetAttnums
};
/*
* Similarly, this enum describes what's kept in the fdw_private list for
* a ForeignScan node that modifies a foreign table directly. We store:
*
* 1) UPDATE/DELETE statement text to be sent to the remote server
* 2) Boolean flag showing if the remote query has a RETURNING clause
* 3) Integer list of attribute numbers retrieved by RETURNING, if any
* 4) Boolean flag showing if we set the command es_processed
*/
enum FdwDirectModifyPrivateIndex
{
/* SQL statement to execute remotely (as a String node) */
FdwDirectModifyPrivateUpdateSql,
/* has-returning flag (as an Boolean node) */
FdwDirectModifyPrivateHasReturning,
/* Integer list of attribute numbers retrieved by RETURNING */
FdwDirectModifyPrivateRetrievedAttrs,
/* set-processed flag (as an Boolean node) */
FdwDirectModifyPrivateSetProcessed,
/* remote conditions */
FdwDirectModifyRemoteExprs
};
/*
* Execution state of a foreign scan that modifies a foreign table directly.
*/
typedef struct InfluxDBFdwDirectModifyState
{
Relation rel; /* relcache entry for the foreign table */
UserMapping *user; /* user mapping of foreign server */
AttInMetadata *attinmeta; /* attribute datatype conversion metadata */
/* extracted fdw_private data */
char *query; /* text of UPDATE/DELETE command */
bool has_returning; /* is there a RETURNING clause? */
List *retrieved_attrs; /* attr numbers retrieved by RETURNING */
bool set_processed; /* do we set the command es_processed? */
/* for remote query execution */
char **params;
int numParams; /* number of parameters passed to query */
FmgrInfo *param_flinfo; /* output conversion functions for them */
List *param_exprs; /* executable expressions for param values */
const char **param_values; /* textual values of query parameters */
Oid *param_types; /* type of query parameters */
InfluxDBType *param_influxdb_types; /* InfluxDB type of query parameters */
InfluxDBValue *param_influxdb_values; /* values for InfluxDB */
InfluxDBColumnInfo *param_column_info; /* information of columns */
influxdb_opt *influxdbFdwOptions; /* InfluxDB FDW options */
/* for storing result tuples */
int num_tuples; /* # of result tuples */
int next_tuple; /* index of next one to return */
Relation resultRel; /* relcache entry for the target relation */
AttrNumber *attnoMap; /* array of attnums of input user columns */
AttrNumber ctidAttno; /* attnum of input ctid column */
AttrNumber oidAttno; /* attnum of input oid column */
bool hasSystemCols; /* are there system columns of resultRel? */
/* working memory context */
MemoryContext temp_cxt; /* context for per-tuple temporary data */
} InfluxDBFdwDirectModifyState;
/*
* Library load-time initialization, sets on_proc_exit() callback for
* backend shutdown.
*/
void
_PG_init(void)
{
on_proc_exit(&influxdb_fdw_exit, PointerGetDatum(NULL));
}
/*
* influxdb_fdw_exit: Exit callback function.
*/
static void
influxdb_fdw_exit(int code, Datum arg)
{
#ifdef CXX_CLIENT
cleanup_cxx_client_connection();
#endif
}
Datum
influxdb_fdw_version(PG_FUNCTION_ARGS)
{
PG_RETURN_INT32(CODE_VERSION);
}
Datum
influxdb_fdw_handler(PG_FUNCTION_ARGS)
{
FdwRoutine *fdwroutine = makeNode(FdwRoutine);
elog(DEBUG1, "influxdb_fdw : %s", __func__);
fdwroutine->GetForeignRelSize = influxdbGetForeignRelSize;
fdwroutine->GetForeignPaths = influxdbGetForeignPaths;
fdwroutine->GetForeignPlan = influxdbGetForeignPlan;
fdwroutine->BeginForeignScan = influxdbBeginForeignScan;
fdwroutine->IterateForeignScan = influxdbIterateForeignScan;
fdwroutine->ReScanForeignScan = influxdbReScanForeignScan;
fdwroutine->EndForeignScan = influxdbEndForeignScan;
/* Functions for updating foreign tables */
fdwroutine->AddForeignUpdateTargets = influxdbAddForeignUpdateTargets;
fdwroutine->PlanForeignModify = influxdbPlanForeignModify;
fdwroutine->BeginForeignModify = influxdbBeginForeignModify;
#if (PG_VERSION_NUM >= 140000)
fdwroutine->ExecForeignBatchInsert = influxdbExecForeignBatchInsert;
fdwroutine->GetForeignModifyBatchSize = influxdbGetForeignModifyBatchSize;
#endif
fdwroutine->ExecForeignInsert = influxdbExecForeignInsert;
fdwroutine->ExecForeignDelete = influxdbExecForeignDelete;
fdwroutine->EndForeignModify = influxdbEndForeignModify;
#if (PG_VERSION_NUM >= 110000)
fdwroutine->BeginForeignInsert = influxdbBeginForeignInsert;
fdwroutine->EndForeignInsert = influxdbEndForeignInsert;
#endif
fdwroutine->PlanDirectModify = influxdbPlanDirectModify;
fdwroutine->BeginDirectModify = influxdbBeginDirectModify;
fdwroutine->IterateDirectModify = influxdbIterateDirectModify;
fdwroutine->EndDirectModify = influxdbEndDirectModify;
/* support for EXPLAIN */
fdwroutine->ExplainForeignScan = influxdbExplainForeignScan;
fdwroutine->ExplainForeignModify = influxdbExplainForeignModify;
fdwroutine->ExplainDirectModify = influxdbExplainDirectModify;
/* support for ANALYSE */
fdwroutine->AnalyzeForeignTable = influxdbAnalyzeForeignTable;
/* support for IMPORT FOREIGN SCHEMA */
fdwroutine->ImportForeignSchema = influxdbImportForeignSchema;
/* Support functions for upper relation push-down */
fdwroutine->GetForeignUpperPaths = influxdbGetForeignUpperPaths;
PG_RETURN_POINTER(fdwroutine);
}
/*
* estimate_path_cost_size
* Get cost and size estimates for a foreign scan on given foreign relation
* either a base relation or a join between foreign relations.
*
* param_join_conds are the parameterization clauses with outer relations.
* pathkeys specify the expected sort order if any for given path being costed.
*
* The function returns the cost and size estimates in p_row, p_width,
* p_startup_cost and p_total_cost variables.
*/
static void
estimate_path_cost_size(PlannerInfo *root,
RelOptInfo *foreignrel,
List *param_join_conds,
List *pathkeys,
double *p_rows, int *p_width,
Cost *p_startup_cost, Cost *p_total_cost)
{
InfluxDBFdwRelationInfo *fpinfo = (InfluxDBFdwRelationInfo *) foreignrel->fdw_private;
double rows;
double retrieved_rows;
int width;
Cost startup_cost;
Cost total_cost;
Cost cpu_per_tuple;
/*
* If the table or the server is configured to use remote estimates,
* connect to the foreign server and execute EXPLAIN to estimate the
* number of rows selected by the restriction+join clauses. Otherwise,
* estimate rows using whatever statistics we have locally, in a way
* similar to ordinary tables.
*/
if (fpinfo->use_remote_estimate)
{
ereport(ERROR, (errmsg("Remote estimation is unsupported")));
}
else
{
Cost run_cost = 0;
/*
* We don't support join conditions in this mode (hence, no
* parameterized paths can be made).
*/
Assert(param_join_conds == NIL);
/*
* Use rows/width estimates made by set_baserel_size_estimates() for
* base foreign relations and set_joinrel_size_estimates() for join
* between foreign relations.
*/
rows = foreignrel->rows;
width = foreignrel->reltarget->width;
/* Back into an estimate of the number of retrieved rows. */
retrieved_rows = clamp_row_est(rows / fpinfo->local_conds_sel);
/*
* We will come here again and again with different set of pathkeys
* that caller wants to cost. We don't need to calculate the cost of
* bare scan each time. Instead, use the costs if we have cached them
* already.
*/
if (fpinfo->rel_startup_cost > 0 && fpinfo->rel_total_cost > 0)
{
startup_cost = fpinfo->rel_startup_cost;
run_cost = fpinfo->rel_total_cost - fpinfo->rel_startup_cost;
}
else
{
Assert(foreignrel->reloptkind != RELOPT_JOINREL);
/* Clamp retrieved rows estimates to at most foreignrel->tuples. */
retrieved_rows = Min(retrieved_rows, foreignrel->tuples);
/*
* Cost as though this were a seqscan, which is pessimistic. We
* effectively imagine the local_conds are being evaluated
* remotely, too.
*/
startup_cost = 0;
run_cost = 0;
run_cost += seq_page_cost * foreignrel->pages;
startup_cost += foreignrel->baserestrictcost.startup;
cpu_per_tuple =
cpu_tuple_cost + foreignrel->baserestrictcost.per_tuple;
run_cost += cpu_per_tuple * foreignrel->tuples;
}
/*
* Without remote estimates, we have no real way to estimate the cost
* of generating sorted output. It could be free if the query plan
* the remote side would have chosen generates properly-sorted output
* anyway, but in most cases it will cost something. Estimate a value
* high enough that we won't pick the sorted path when the ordering
* isn't locally useful, but low enough that we'll err on the side of
* pushing down the ORDER BY clause when it's useful to do so.
*/
if (pathkeys != NIL)
{
startup_cost *= DEFAULT_FDW_SORT_MULTIPLIER;
run_cost *= DEFAULT_FDW_SORT_MULTIPLIER;
}
total_cost = startup_cost + run_cost;
}
/*
* Cache the costs for scans without any pathkeys or parameterization
* before adding the costs for transferring data from the foreign server.
* These costs are useful for costing the join between this relation and
* another foreign relation or to calculate the costs of paths with
* pathkeys for this relation, when the costs can not be obtained from the
* foreign server. This function will be called at least once for every
* foreign relation without pathkeys and parameterization.
*/
if (pathkeys == NIL && param_join_conds == NIL)
{
fpinfo->rel_startup_cost = startup_cost;
fpinfo->rel_total_cost = total_cost;
}
/*
* Add some additional cost factors to account for connection overhead
* (fdw_startup_cost), transferring data across the network
* (fdw_tuple_cost per retrieved row), and local manipulation of the data
* (cpu_tuple_cost per retrieved row).
*/
startup_cost += fpinfo->fdw_startup_cost;
total_cost += fpinfo->fdw_startup_cost;
total_cost += fpinfo->fdw_tuple_cost * retrieved_rows;
total_cost += cpu_tuple_cost * retrieved_rows;
/* Return results. */
*p_rows = rows;
*p_width = width;
*p_startup_cost = startup_cost;
*p_total_cost = total_cost;
}
/*
* influxdb_extract_slcols: Extract actual remote InfluxDB columns that being fetched.
*/
static void
influxdb_extract_slcols(InfluxDBFdwRelationInfo *fpinfo, PlannerInfo *root, RelOptInfo *baserel, List *tlist)
{
RangeTblEntry *rte;
List *input_tlist = (tlist) ? tlist : baserel->reltarget->exprs;
ListCell *lc = NULL;
if (!fpinfo->slinfo.schemaless)
return;
rte = planner_rt_fetch(baserel->relid, root);
fpinfo->all_fieldtag = influxdb_is_select_all(rte, input_tlist, &fpinfo->slinfo);
/* All actual column is required to be selected */
if (fpinfo->all_fieldtag)
return;
/* Extract jsonb schemaless variable names from tlist */
fpinfo->slcols = NIL;
fpinfo->slcols = influxdb_pull_slvars((Expr *)input_tlist, baserel->relid,
fpinfo->slcols, false, NULL, &(fpinfo->slinfo));
/* Append josnb schemaless variable names from local_conds. */
foreach(lc, fpinfo->local_conds)
{
RestrictInfo *ri = (RestrictInfo *) lfirst(lc);
fpinfo->slcols = influxdb_pull_slvars(ri->clause, baserel->relid,
fpinfo->slcols, false, NULL, &(fpinfo->slinfo));
}
}
/*
* influxdbGetForeignRelSize: Create a FdwPlan for a scan on the foreign table
*/
static void
influxdbGetForeignRelSize(PlannerInfo *root, RelOptInfo *baserel, Oid foreigntableid)
{
InfluxDBFdwRelationInfo *fpinfo;
influxdb_opt *options;
ListCell *lc;
Oid userid;
#if PG_VERSION_NUM < 160000
RangeTblEntry *rte = planner_rt_fetch(baserel->relid, root);
#endif
elog(DEBUG1, "influxdb_fdw : %s", __func__);
fpinfo = (InfluxDBFdwRelationInfo *) palloc0(sizeof(InfluxDBFdwRelationInfo));
baserel->fdw_private = (void *) fpinfo;
#if PG_VERSION_NUM >= 160000
userid = OidIsValid(baserel->userid) ? baserel->userid : GetUserId();
#else
userid = rte->checkAsUser ? rte->checkAsUser : GetUserId();
#endif
/* Fetch the options */
options = influxdb_get_options(foreigntableid, userid);
influxdb_get_schemaless_info(&(fpinfo->slinfo), options->schemaless, foreigntableid);
/* Base foreign tables need to be pushed down always. */
fpinfo->pushdown_safe = true;
/* Look up foreign-table catalog info. */
fpinfo->table = GetForeignTable(foreigntableid);
fpinfo->server = GetForeignServer(fpinfo->table->serverid);
/*
* Identify which baserestrictinfo clauses can be sent to the remote
* server and which can't.
*/
foreach(lc, baserel->baserestrictinfo)
{
RestrictInfo *ri = (RestrictInfo *) lfirst(lc);
if (influxdb_is_foreign_expr(root, baserel, ri->clause, false))
fpinfo->remote_conds = lappend(fpinfo->remote_conds, ri);
else
fpinfo->local_conds = lappend(fpinfo->local_conds, ri);
}
/*
* Identify which attributes will need to be retrieved from the remote
* server.
*/
pull_varattnos((Node *) baserel->reltarget->exprs, baserel->relid, &fpinfo->attrs_used);
foreach(lc, fpinfo->local_conds)
{
RestrictInfo *rinfo = (RestrictInfo *) lfirst(lc);
pull_varattnos((Node *) rinfo->clause, baserel->relid, &fpinfo->attrs_used);
}
/*
* Compute the selectivity and cost of the local_conds, so we don't have
* to do it over again for each path. The best we can do for these
* conditions is to estimate selectivity on the basis of local statistics.
*/
fpinfo->local_conds_sel = clauselist_selectivity(root,
fpinfo->local_conds,
baserel->relid,
JOIN_INNER,
NULL);
/*
* Set cached relation costs to some negative value, so that we can detect
* when they are set to some sensible costs during one (usually the first)
* of the calls to estimate_path_cost_size().
*/
fpinfo->rel_startup_cost = -1;
fpinfo->rel_total_cost = -1;
/*
* If the table or the server is configured to use remote estimates,
* connect to the foreign server and execute EXPLAIN to estimate the
* number of rows selected by the restriction clauses, as well as the
* average row width. Otherwise, estimate using whatever statistics we
* have locally, in a way similar to ordinary tables.
*/
if (fpinfo->use_remote_estimate)
{
ereport(ERROR, (errmsg("Remote estimation is unsupported")));
}
else
{
/*
* We can't do much if we're not allowed to consult the remote server,
* but we can use a hack similar to plancat.c's treatment of empty
* relations: use a minimum size estimate of 10 pages, and divide by
* the column-datatype-based width estimate to get the corresponding
* number of tuples.
*/
#if (PG_VERSION_NUM < 140000)
/*
* If the foreign table has never been ANALYZEd, it will have relpages
* and reltuples equal to zero, which most likely has nothing to do
* with reality.
*/
if (baserel->pages == 0 && baserel->tuples == 0)
#else
/*
* If the foreign table has never been ANALYZEd, it will have
* reltuples < 0, meaning "unknown"
*/
if (baserel->tuples < 0)
#endif
{
baserel->pages = 10;
baserel->tuples =
(10 * BLCKSZ) / (baserel->reltarget->width +
MAXALIGN(SizeofHeapTupleHeader));
}
/* Estimate baserel size as best we can with local statistics. */
set_baserel_size_estimates(root, baserel);
/* Fill in basically-bogus cost estimates for use later. */
estimate_path_cost_size(root, baserel, NIL, NIL,
&fpinfo->rows, &fpinfo->width,
&fpinfo->startup_cost, &fpinfo->total_cost);
}
/*
* Set the name of relation in fpinfo, while we are constructing it here.
* It will be used to build the string describing the join relation in
* EXPLAIN output. We can't know whether VERBOSE option is specified or
* not, so always schema-qualify the foreign table name.
*/
fpinfo->relation_name = psprintf("%u", baserel->relid);
}
/*
* influxdbGetForeignPaths
* Create possible scan paths for a scan on the foreign table
*/
static void
influxdbGetForeignPaths(PlannerInfo *root, RelOptInfo *baserel, Oid foreigntableid)
{
Cost startup_cost = 10;
Cost total_cost = baserel->rows + startup_cost;
elog(DEBUG1, "influxdb_fdw : %s", __func__);
/* Estimate costs */
total_cost = baserel->rows;
/* Create a ForeignPath node and add it as only possible path */
add_path(baserel, (Path *)
create_foreignscan_path(root, baserel,
NULL, /* default pathtarget */
baserel->rows,
startup_cost,
total_cost,
NIL, /* no pathkeys */
#if (PG_VERSION_NUM >= 120000)
baserel->lateral_relids,
#else
NULL, /* no outer rel either */
#endif
NULL, /* no extra plan */
NULL)); /* no fdw_private data */
}
/*
* influxdbGetForeignPlan: Get a foreign scan plan node
*/
static ForeignScan *
influxdbGetForeignPlan(PlannerInfo *root,
RelOptInfo *baserel,
Oid foreigntableid,
ForeignPath *best_path,
List *tlist,
List *scan_clauses,
Plan *outer_plan)
{
InfluxDBFdwRelationInfo *fpinfo = (InfluxDBFdwRelationInfo *) baserel->fdw_private;
Index scan_relid = baserel->relid;
List *fdw_private = NULL;
List *local_exprs = NULL;
List *remote_exprs = NULL;
List *params_list = NULL;
List *fdw_scan_tlist = NIL;
List *remote_conds = NIL;
StringInfoData sql;
List *retrieved_attrs;
ListCell *lc;
List *fdw_recheck_quals = NIL;
int for_update;
bool has_limit = false;
elog(DEBUG1, "influxdb_fdw : %s", __func__);
/* Decide to execute function pushdown support in the target list. */
fpinfo->is_tlist_func_pushdown = influxdb_is_foreign_function_tlist(root, baserel, tlist);
/*
* Get FDW private data created by influxdbGetForeignUpperPaths(), if any.
*/
if (best_path->fdw_private)
{
#if (PG_VERSION_NUM >= 150000)
has_limit = boolVal(list_nth(best_path->fdw_private, FdwPathPrivateHasLimit));
#else
has_limit = intVal(list_nth(best_path->fdw_private, FdwPathPrivateHasLimit));
#endif
}
/*
* Build the query string to be sent for execution, and identify
* expressions to be sent as parameters.
*/
/* Build the query */
initStringInfo(&sql);
/*
* Separate the scan_clauses into those that can be executed remotely and
* those that can't. baserestrictinfo clauses that were previously
* determined to be safe or unsafe by classifyConditions are shown in
* fpinfo->remote_conds and fpinfo->local_conds. Anything else in the
* scan_clauses list will be a join clause, which we have to check for
* remote-safety.
*
* Note: the join clauses we see here should be the exact same ones
* previously examined by influxdbGetForeignPaths. Possibly it'd be worth
* passing forward the classification work done then, rather than
* repeating it here.
*
* This code must match "extract_actual_clauses(scan_clauses, false)"
* except for the additional decision about remote versus local execution.
* Note however that we only strip the RestrictInfo nodes from the
* local_exprs list, since appendWhereClause expects a list of
* RestrictInfos.
*/
if ((baserel->reloptkind == RELOPT_BASEREL ||
baserel->reloptkind == RELOPT_OTHER_MEMBER_REL) &&
fpinfo->is_tlist_func_pushdown == false)
{
/* Extract actual remote InfluxDB columns that being fetched. */
influxdb_extract_slcols(fpinfo, root, baserel, tlist);
foreach(lc, scan_clauses)
{
RestrictInfo *rinfo = (RestrictInfo *) lfirst(lc);
Assert(IsA(rinfo, RestrictInfo));
/* Ignore any pseudoconstants, they're dealt with elsewhere */
if (rinfo->pseudoconstant)
continue;
if (list_member_ptr(fpinfo->remote_conds, rinfo))
{
remote_exprs = lappend(remote_exprs, rinfo->clause);
}
else if (list_member_ptr(fpinfo->local_conds, rinfo))
local_exprs = lappend(local_exprs, rinfo->clause);
else if (influxdb_is_foreign_expr(root, baserel, rinfo->clause, false))
{
remote_exprs = lappend(remote_exprs, rinfo->clause);
}
else
local_exprs = lappend(local_exprs, rinfo->clause);
/*
* For a base-relation scan, we have to support EPQ recheck, which
* should recheck all the remote quals.
*/
fdw_recheck_quals = remote_exprs;
}
}
else
{
/*
* Join relation or upper relation - set scan_relid to 0.
*/
scan_relid = 0;
/*
* For a join rel, baserestrictinfo is NIL and we are not considering
* parameterization right now, so there should be no scan_clauses for
* a joinrel or an upper rel either.
*/
if (fpinfo->is_tlist_func_pushdown == false)
{
Assert(!scan_clauses);
}
/*
* Instead we get the conditions to apply from the fdw_private
* structure.
*/
remote_exprs = extract_actual_clauses(fpinfo->remote_conds, false);
local_exprs = extract_actual_clauses(fpinfo->local_conds, false);
/*
* We leave fdw_recheck_quals empty in this case, since we never need
* to apply EPQ recheck clauses. In the case of a joinrel, EPQ
* recheck is handled elsewhere --- see influxdbGetForeignJoinPaths().
* If we're planning an upperrel (ie, remote grouping or aggregation)
* then there's no EPQ to do because SELECT FOR UPDATE wouldn't be
* allowed, and indeed we *can't* put the remote clauses into
* fdw_recheck_quals because the unaggregated Vars won't be available
* locally.
*/
/* Build the list of columns to be fetched from the foreign server. */
if (fpinfo->is_tlist_func_pushdown == true)
{
foreach(lc, tlist)
{
TargetEntry *tle = lfirst_node(TargetEntry, lc);
/*
* Pull out function from FieldSelect clause and add to
* fdw_scan_tlist to push down function portion only
*/
if (fpinfo->is_tlist_func_pushdown == true && IsA((Node *) tle->expr, FieldSelect))
{
fdw_scan_tlist = add_to_flat_tlist(fdw_scan_tlist,
influxdb_pull_func_clause((Node *) tle->expr));
}
else
{
fdw_scan_tlist = lappend(fdw_scan_tlist, tle);
}
}
foreach(lc, fpinfo->local_conds)
{
RestrictInfo *rinfo = lfirst_node(RestrictInfo, lc);
List *varlist = NIL;
varlist = influxdb_pull_slvars(rinfo->clause, baserel->relid,
varlist, true, NULL, &(fpinfo->slinfo));
if (varlist == NIL)
varlist = pull_var_clause((Node *) rinfo->clause,
PVC_RECURSE_PLACEHOLDERS);
fdw_scan_tlist = add_to_flat_tlist(fdw_scan_tlist, varlist);
}
}
else
{
fdw_scan_tlist = influxdb_build_tlist_to_deparse(baserel);
}
/*
* Ensure that the outer plan produces a tuple whose descriptor
* matches our scan tuple slot. This is safe because all scans and
* joins support projection, so we never need to insert a Result node.
* Also, remove the local conditions from outer plan's quals, lest
* they will be evaluated twice, once by the local plan and once by
* the scan.
*/
if (outer_plan)
{
/*
* Right now, we only consider grouping and aggregation beyond
* joins. Queries involving aggregates or grouping do not require
* EPQ mechanism, hence should not have an outer plan here.
*/
Assert(baserel->reloptkind != RELOPT_UPPER_REL);
outer_plan->targetlist = fdw_scan_tlist;
foreach(lc, local_exprs)
{
Join *join_plan = (Join *) outer_plan;
Node *qual = lfirst(lc);
outer_plan->qual = list_delete(outer_plan->qual, qual);
/*
* For an inner join the local conditions of foreign scan plan
* can be part of the joinquals as well.
*/
if (join_plan->jointype == JOIN_INNER)
join_plan->joinqual = list_delete(join_plan->joinqual,
qual);
}
}
}