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sqlite_fdw.c
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sqlite_fdw.c
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/*-------------------------------------------------------------------------
*
* SQLite Foreign Data Wrapper for PostgreSQL
*
* Portions Copyright (c) 2018, TOSHIBA CORPORATION
*
* IDENTIFICATION
* sqlite_fdw.c
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "sqlite_fdw.h"
#include <sqlite3.h>
#include "catalog/pg_collation.h"
#include "catalog/pg_type.h"
#include "commands/defrem.h"
#include "commands/explain.h"
#include "foreign/fdwapi.h"
#include "funcapi.h"
#include "mb/pg_wchar.h"
#include "miscadmin.h"
#include "nodes/makefuncs.h"
#include "nodes/nodeFuncs.h"
#if (PG_VERSION_NUM < 140000)
#include "optimizer/clauses.h"
#endif
#include "optimizer/pathnode.h"
#if PG_VERSION_NUM >= 120000
#include "optimizer/appendinfo.h"
#endif
#include "optimizer/planmain.h"
#include "optimizer/planner.h"
#include "optimizer/cost.h"
#if (PG_VERSION_NUM >= 130010 && PG_VERSION_NUM < 140000) || \
(PG_VERSION_NUM >= 140007 && PG_VERSION_NUM < 150000) || \
(PG_VERSION_NUM >= 150002)
#include "optimizer/inherit.h"
#endif
#include "optimizer/paths.h"
#include "optimizer/prep.h"
#include "optimizer/restrictinfo.h"
#include "optimizer/tlist.h"
#include "parser/parsetree.h"
#include "parser/parse_type.h"
#include "storage/ipc.h"
#include "utils/builtins.h"
#include "utils/formatting.h"
#include "utils/guc.h"
#include "utils/lsyscache.h"
#include "utils/selfuncs.h"
extern PGDLLEXPORT void _PG_init(void);
static void sqlite_fdw_exit(int code, Datum arg);
PG_MODULE_MAGIC;
/* The number of default estimated rows for table which does not exist in sqlite1_stat1
* See sqlite3ResultSetOfSelect in select.c of SQLite
*/
#define DEFAULT_ROW_ESTIMATE 1000000
#define DEFAULTE_NUM_ROWS 1000
#define IS_KEY_COLUMN(A) ((strcmp(A->defname, "key") == 0) && \
(strcmp(strVal(A->arg), "true") == 0))
/* 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
/*
* 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 an integer Value node) */
FdwPathPrivateHasFinalSort,
/* has-limit flag (as an integer Value node) */
FdwPathPrivateHasLimit
};
/*
* Indexes of FDW-private information stored in fdw_private lists.
*
* These items are indexed with the enum FdwScanPrivateIndex, so an item
* can be fetched with list_nth(). For example, to get the SELECT statement:
* sql = strVal(list_nth(fdw_private, FdwScanPrivateSelectSql));
*/
enum FdwScanPrivateIndex
{
/* SQL statement to execute remotely (as a String node) */
FdwScanPrivateSelectSql,
/* Integer list of attribute numbers retrieved by the SELECT */
FdwScanPrivateRetrievedAttrs,
/* Integer representing UPDATE/DELETE target */
FdwScanPrivateForUpdate,
#if (PG_VERSION_NUM < 100000)
/* rtindex */
FdwScanPrivateRtIndex,
#endif
/*
* String describing join i.e. names of relations being joined and types
* of join, added when the scan is join
*/
FdwScanPrivateRelations
};
/*
* Similarly, this enum describes what's kept in the fdw_private list for
* a ModifyTable node referencing a sqlite_fdw foreign table. We store:
*
* 1) INSERT/UPDATE/DELETE statement text to be sent to the remote server
* 2) Integer list of target attribute numbers for INSERT/UPDATE
* (NIL for a DELETE)
* 3) Length till the end of VALUES clause for INSERT
* (-1 for a DELETE/UPDATE)
*/
enum FdwModifyPrivateIndex
{
/* SQL statement to execute remotely (as a String node) */
FdwModifyPrivateUpdateSql,
/* Integer list of target attribute numbers for INSERT/UPDATE */
FdwModifyPrivateTargetAttnums,
/* Length till the end of VALUES clause (as an Integer node) */
FdwModifyPrivateLen
};
/*
* 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 a Boolean node) */
FdwDirectModifyPrivateHasReturning,
/* Integer list of attribute numbers retrieved by RETURNING */
FdwDirectModifyPrivateRetrievedAttrs,
/* set-processed flag (as a Boolean node) */
FdwDirectModifyPrivateSetProcessed
};
extern PGDLLEXPORT Datum sqlite_fdw_handler(PG_FUNCTION_ARGS);
PG_FUNCTION_INFO_V1(sqlite_fdw_handler);
PG_FUNCTION_INFO_V1(sqlite_fdw_version);
static void sqliteGetForeignRelSize(PlannerInfo *root,
RelOptInfo *baserel,
Oid foreigntableid);
static void sqliteGetForeignPaths(PlannerInfo *root,
RelOptInfo *baserel,
Oid foreigntableid);
static ForeignScan *sqliteGetForeignPlan(PlannerInfo *root,
RelOptInfo *baserel,
Oid foreigntableid,
ForeignPath *best_path,
List *tlist,
List *scan_clauses,
Plan *outer_plan);
static void sqliteBeginForeignScan(ForeignScanState *node,
int eflags);
static TupleTableSlot *sqliteIterateForeignScan(ForeignScanState *node);
static void sqliteReScanForeignScan(ForeignScanState *node);
static void sqliteEndForeignScan(ForeignScanState *node);
static void sqliteAddForeignUpdateTargets(
#if (PG_VERSION_NUM >= 140000)
PlannerInfo *root,
Index rtindex,
#else
Query *parsetree,
#endif
RangeTblEntry *target_rte,
Relation target_relation);
static List *sqlitePlanForeignModify(PlannerInfo *root,
ModifyTable *plan,
Index resultRelation,
int subplan_index);
static void sqliteBeginForeignModify(ModifyTableState *mtstate,
ResultRelInfo *rinfo,
List *fdw_private,
int subplan_index,
int eflags);
static TupleTableSlot *sqliteExecForeignInsert(EState *estate,
ResultRelInfo *rinfo,
TupleTableSlot *slot,
TupleTableSlot *planSlot);
#if PG_VERSION_NUM >= 140000
static TupleTableSlot **sqliteExecForeignBatchInsert(EState *estate,
ResultRelInfo *resultRelInfo,
TupleTableSlot **slots,
TupleTableSlot **planSlots,
int *numSlots);
static int sqliteGetForeignModifyBatchSize(ResultRelInfo *resultRelInfo);
#endif
static TupleTableSlot *sqliteExecForeignUpdate(EState *estate,
ResultRelInfo *rinfo,
TupleTableSlot *slot,
TupleTableSlot *planSlot);
static TupleTableSlot *sqliteExecForeignDelete(EState *estate,
ResultRelInfo *rinfo,
TupleTableSlot *slot,
TupleTableSlot *planSlot);
static void sqliteEndForeignModify(EState *estate,
ResultRelInfo *rinfo);
#if (PG_VERSION_NUM >= 110000)
static void sqliteEndForeignInsert(EState *estate,
ResultRelInfo *resultRelInfo);
static void sqliteBeginForeignInsert(ModifyTableState *mtstate,
ResultRelInfo *resultRelInfo);
#endif
static void sqliteExplainForeignScan(ForeignScanState *node,
struct ExplainState *es);
static void sqliteExplainForeignModify(ModifyTableState *mtstate,
ResultRelInfo *rinfo,
List *fdw_private,
int subplan_index,
struct ExplainState *es);
static bool sqlitePlanDirectModify(PlannerInfo *root,
ModifyTable *plan,
Index resultRelation,
int subplan_index);
static void sqliteBeginDirectModify(ForeignScanState *node, int eflags);
static TupleTableSlot *sqliteIterateDirectModify(ForeignScanState *node);
static void sqliteEndDirectModify(ForeignScanState *node);
static void sqliteExplainDirectModify(ForeignScanState *node,
struct ExplainState *es);
#if PG_VERSION_NUM >= 140000
static void sqliteExecForeignTruncate(List *rels,
DropBehavior behavior,
bool restart_seqs);
#endif
static bool sqliteAnalyzeForeignTable(Relation relation,
AcquireSampleRowsFunc *func,
BlockNumber *totalpages);
static int sqliteIsForeignRelUpdatable(Relation rel);
static List *sqliteImportForeignSchema(ImportForeignSchemaStmt *stmt,
Oid serverOid);
static void sqliteGetForeignJoinPaths(PlannerInfo *root,
RelOptInfo *joinrel,
RelOptInfo *outerrel,
RelOptInfo *innerrel,
JoinType jointype,
JoinPathExtraData *extra);
static void
sqliteGetForeignUpperPaths(PlannerInfo *root,
UpperRelationKind stage,
RelOptInfo *input_rel,
RelOptInfo *output_rel
#if (PG_VERSION_NUM >= 110000)
,void *extra
#endif
);
static void sqlite_prepare_wrapper(ForeignServer *server,
sqlite3 * db, char *query,
sqlite3_stmt * *result,
const char **pzTail,
bool is_cache);
static void sqlite_to_pg_type(StringInfo str, char *typname);
static TupleTableSlot **sqlite_execute_insert(EState *estate,
ResultRelInfo *resultRelInfo,
CmdType operation,
TupleTableSlot **slots,
TupleTableSlot **planSlots,
int *numSlots);
static void sqlite_prepare_query_params(PlanState *node,
List *fdw_exprs,
int numParams,
FmgrInfo **param_flinfo,
List **param_exprs,
const char ***param_values,
Oid **param_types);
static void sqlite_process_query_params(ExprContext *econtext,
FmgrInfo *param_flinfo,
List *param_exprs,
const char **param_values,
sqlite3_stmt * *stmt,
Oid *param_types,
Oid foreignTableId);
static void sqlite_create_cursor(ForeignScanState *node);
static void sqlite_execute_dml_stmt(ForeignScanState *node);
static void sqlite_merge_fdw_options(SqliteFdwRelationInfo * fpinfo,
const SqliteFdwRelationInfo * fpinfo_o,
const SqliteFdwRelationInfo * fpinfo_i);
static bool sqlite_foreign_grouping_ok(PlannerInfo *root, RelOptInfo *grouped_rel);
static void sqlite_add_foreign_grouping_paths(PlannerInfo *root,
RelOptInfo *input_rel,
RelOptInfo *grouped_rel
#if (PG_VERSION_NUM >= 110000)
,GroupPathExtraData *extra
#endif
);
static void sqlite_add_foreign_ordered_paths(PlannerInfo *root,
RelOptInfo *input_rel,
RelOptInfo *ordered_rel);
static void sqlite_add_foreign_final_paths(PlannerInfo *root,
RelOptInfo *input_rel,
RelOptInfo *final_rel
#if (PG_VERSION_NUM >= 120000)
,FinalPathExtraData *extra
#endif
);
static void sqlite_get_remote_estimate(const char *sql,
sqlite3 * conn,
double *rows,
int *width,
Cost *startup_cost,
Cost *total_cost);
static void sqlite_estimate_path_cost_size(PlannerInfo *root,
RelOptInfo *foreignrel,
List *param_join_conds,
List *pathkeys,
SqliteFdwPathExtraData * fpextra,
double *p_rows, int *p_width,
Cost *p_startup_cost, Cost *p_total_cost);
static bool sqlite_foreign_join_ok(PlannerInfo *root, RelOptInfo *joinrel,
JoinType jointype, RelOptInfo *outerrel, RelOptInfo *innerrel,
JoinPathExtraData *extra);
static void sqlite_adjust_foreign_grouping_path_cost(PlannerInfo *root,
List *pathkeys,
double retrieved_rows,
double width,
double limit_tuples,
Cost *p_startup_cost,
Cost *p_run_cost);
static bool sqlite_ec_member_matches_foreign(PlannerInfo *root, RelOptInfo *rel,
EquivalenceClass *ec, EquivalenceMember *em,
void *arg);
static bool sqlite_all_baserels_are_foreign(PlannerInfo *root);
static void sqlite_add_paths_with_pathkeys_for_rel(PlannerInfo *root, RelOptInfo *rel, List *fdw_private, Path *epq_path);
static List *sqlite_get_useful_pathkeys_for_relation(PlannerInfo *root,
RelOptInfo *rel);
#if PG_VERSION_NUM >= 140000
static int sqlite_get_batch_size_option(Relation rel);
#endif
static void conversion_error_callback(void *arg);
static int32 sqlite_affinity_eqv_to_pgtype(Oid type);
const char* sqlite_datatype(int t);
/* Callback argument for sqlite_ec_member_matches_foreign */
typedef struct
{
Expr *current; /* current expr, or NULL if not yet found */
List *already_used; /* expressions already dealt with */
} ec_member_foreign_arg;
/*
* Identify the attribute where data conversion fails.
*/
typedef struct ConversionLocation
{
AttrNumber cur_attno; /* attribute number being processed, or 0 */
Relation rel; /* foreign table being processed, or NULL */
ForeignScanState *fsstate; /* plan node being processed, or NULL */
Form_pg_attribute att; /* PostgreSQL relation attribute */
sqlite3_value *val; /* abstract SQLite value to get affinity, length and text value */
} ConversionLocation;
/*
* Library load-time initialization, sets on_proc_exit() callback for
* backend shutdown.
*/
void
_PG_init(void)
{
on_proc_exit(&sqlite_fdw_exit, PointerGetDatum(NULL));
}
/*
* sqlite_fdw_exit: Exit callback function.
*/
static void
sqlite_fdw_exit(int code, Datum arg)
{
sqlite_cleanup_connection();
}
Datum
sqlite_fdw_handler(PG_FUNCTION_ARGS)
{
FdwRoutine *fdwroutine = makeNode(FdwRoutine);
elog(DEBUG1, "sqlite_fdw : %s", __func__);
fdwroutine->GetForeignRelSize = sqliteGetForeignRelSize;
fdwroutine->GetForeignPaths = sqliteGetForeignPaths;
fdwroutine->GetForeignPlan = sqliteGetForeignPlan;
fdwroutine->BeginForeignScan = sqliteBeginForeignScan;
fdwroutine->IterateForeignScan = sqliteIterateForeignScan;
fdwroutine->ReScanForeignScan = sqliteReScanForeignScan;
fdwroutine->EndForeignScan = sqliteEndForeignScan;
fdwroutine->IsForeignRelUpdatable = sqliteIsForeignRelUpdatable;
fdwroutine->AddForeignUpdateTargets = sqliteAddForeignUpdateTargets;
fdwroutine->PlanForeignModify = sqlitePlanForeignModify;
fdwroutine->BeginForeignModify = sqliteBeginForeignModify;
fdwroutine->ExecForeignInsert = sqliteExecForeignInsert;
#if PG_VERSION_NUM >= 140000
fdwroutine->ExecForeignBatchInsert = sqliteExecForeignBatchInsert;
fdwroutine->GetForeignModifyBatchSize = sqliteGetForeignModifyBatchSize;
#endif
fdwroutine->ExecForeignUpdate = sqliteExecForeignUpdate;
fdwroutine->ExecForeignDelete = sqliteExecForeignDelete;
fdwroutine->EndForeignModify = sqliteEndForeignModify;
#if (PG_VERSION_NUM >= 110000)
fdwroutine->BeginForeignInsert = sqliteBeginForeignInsert;
fdwroutine->EndForeignInsert = sqliteEndForeignInsert;
#endif
/* Support functions for join push-down */
fdwroutine->GetForeignJoinPaths = sqliteGetForeignJoinPaths;
/* support for EXPLAIN */
fdwroutine->ExplainForeignScan = sqliteExplainForeignScan;
fdwroutine->ExplainForeignModify = sqliteExplainForeignModify;
fdwroutine->ExplainDirectModify = sqliteExplainDirectModify;
#if PG_VERSION_NUM >= 140000
/* Support function for TRUNCATE */
fdwroutine->ExecForeignTruncate = sqliteExecForeignTruncate;
#endif
/* suport for Direct Modification */
fdwroutine->PlanDirectModify = sqlitePlanDirectModify;
fdwroutine->BeginDirectModify = sqliteBeginDirectModify;
fdwroutine->IterateDirectModify = sqliteIterateDirectModify;
fdwroutine->EndDirectModify = sqliteEndDirectModify;
/* support for ANALYSE */
fdwroutine->AnalyzeForeignTable = sqliteAnalyzeForeignTable;
/* support for IMPORT FOREIGN SCHEMA */
fdwroutine->ImportForeignSchema = sqliteImportForeignSchema;
/* Support functions for upper relation push-down */
fdwroutine->GetForeignUpperPaths = sqliteGetForeignUpperPaths;
PG_RETURN_POINTER(fdwroutine);
}
Datum
sqlite_fdw_version(PG_FUNCTION_ARGS)
{
PG_RETURN_INT32(CODE_VERSION);
}
/* Wrapper for sqlite3_prepare */
static void
sqlite_prepare_wrapper(ForeignServer *server, sqlite3 * db, char *query, sqlite3_stmt * *stmt,
const char **pzTail, bool is_cache)
{
int rc;
elog(DEBUG1, "sqlite_fdw : %s %s\n", __func__, query);
rc = sqlite3_prepare_v2(db, query, -1, stmt, pzTail);
if (rc != SQLITE_OK)
{
ereport(ERROR,
(errcode(ERRCODE_FDW_UNABLE_TO_CREATE_EXECUTION),
errmsg("SQL error during prepare: %s %s", sqlite3_errmsg(db), query)
));
}
/* cache stmt to finalize at last */
if (is_cache)
sqlite_cache_stmt(server, stmt);
}
/*
* sqliteGetForeignRelSize: Create a FdwPlan for a scan on the foreign table
*/
static void
sqliteGetForeignRelSize(PlannerInfo *root, RelOptInfo *baserel, Oid foreigntableid)
{
SqliteFdwRelationInfo *fpinfo;
ListCell *lc;
#if PG_VERSION_NUM < 160000
RangeTblEntry *rte = planner_rt_fetch(baserel->relid, root);
#endif
elog(DEBUG1, "sqlite_fdw : %s", __func__);
fpinfo = (SqliteFdwRelationInfo *) palloc0(sizeof(SqliteFdwRelationInfo));
baserel->fdw_private = (void *) fpinfo;
/* 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);
/*
* Extract user-settable option values. Note that per-table setting of
* use_remote_estimate overrides per-server setting.
*/
fpinfo->use_remote_estimate = false;
fpinfo->fdw_startup_cost = DEFAULT_FDW_STARTUP_COST;
fpinfo->fdw_tuple_cost = DEFAULT_FDW_TUPLE_COST;
/*
* If the table or the server is configured to use remote estimates,
* identify which user to do remote access as during planning.
* This should match what ExecCheckPermissions() does (ExecCheckRTEPerms() for older version).
* If we fail due to lack of permissions, the query would have failed at runtime anyway.
*/
if (fpinfo->use_remote_estimate)
{
#if (PG_VERSION_NUM < 160000)
Oid userid = rte->checkAsUser ? rte->checkAsUser : GetUserId();
#else
Oid userid;
userid = OidIsValid(baserel->userid) ? baserel->userid : GetUserId();
#endif
fpinfo->user = GetUserMapping(userid, fpinfo->server->serverid);
}
else
fpinfo->user = NULL;
/*
* Identify which baserestrictinfo clauses can be sent to the remote
* server and which can't.
*/
sqlite_classify_conditions(root, baserel, baserel->baserestrictinfo,
&fpinfo->remote_conds, &fpinfo->local_conds);
/*
* Identify which attributes will need to be retrieved from the remote
* server.
*/
fpinfo->attrs_used = NULL;
#if PG_VERSION_NUM >= 90600
pull_varattnos((Node *) baserel->reltarget->exprs, baserel->relid, &fpinfo->attrs_used);
#else
pull_varattnos((Node *) baserel->reltargetlist, baserel->relid, &fpinfo->attrs_used);
#endif
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);
cost_qual_eval(&fpinfo->local_conds_cost, fpinfo->local_conds, root);
/*
* Set # of retrieved rows and cached relation costs to some negative
* value, so that we can detect when they are set to some sensible values,
* during one (usually the first) of the calls to
* sqlite_estimate_path_cost_size.
*/
fpinfo->retrieved_rows = -1;
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)
{
/*
* Get cost/size estimates with help of remote server. Save the
* values in fpinfo so we don't need to do it again to generate the
* basic foreign path.
*/
sqlite_estimate_path_cost_size(root, baserel, NIL, NIL, NULL,
&fpinfo->rows, &fpinfo->width,
&fpinfo->startup_cost, &fpinfo->total_cost);
/* Report estimated baserel size to planner. */
baserel->rows = fpinfo->rows;
baserel->reltarget->width = fpinfo->width;
}
else
{
/*
* 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. We can't do a whole lot about that 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 (baserel->tuples < 0)
#else
if (baserel->pages == 0 && 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. */
sqlite_estimate_path_cost_size(root, baserel, NIL, NIL, NULL,
&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);
/* No outer and inner relations. */
fpinfo->make_outerrel_subquery = false;
fpinfo->make_innerrel_subquery = false;
fpinfo->lower_subquery_rels = NULL;
/* Set the relation index. */
fpinfo->relation_index = baserel->relid;
}
/*
* sqlite_get_useful_pathkeys_for_relation
* Determine which orderings of a relation might be useful.
*
* Getting data in sorted order can be useful either because the requested
* order matches the final output ordering for the overall query we're
* planning, or because it enables an efficient merge join. Here, we try
* to figure out which pathkeys to consider.
*/
static List *
sqlite_get_useful_pathkeys_for_relation(PlannerInfo *root, RelOptInfo *rel)
{
List *useful_pathkeys_list = NIL;
SqliteFdwRelationInfo *fpinfo = (SqliteFdwRelationInfo *) rel->fdw_private;
ListCell *lc;
/*
* Pushing the query_pathkeys to the remote server is always worth
* considering, because it might let us avoid a local sort.
*/
fpinfo->qp_is_pushdown_safe = false;
if (root->query_pathkeys)
{
bool query_pathkeys_ok = true;
foreach(lc, root->query_pathkeys)
{
PathKey *pathkey = (PathKey *) lfirst(lc);
/*
* The planner and executor don't have any clever strategy for
* taking data sorted by a prefix of the query's pathkeys and
* getting it to be sorted by all of those pathkeys. We'll just
* end up resorting the entire data set. So, unless we can push
* down all of the query pathkeys, forget it.
*/
if (!sqlite_is_foreign_pathkey(root, rel, pathkey))
{
query_pathkeys_ok = false;
break;
}
}
if (query_pathkeys_ok)
{
useful_pathkeys_list = list_make1(list_copy(root->query_pathkeys));
fpinfo->qp_is_pushdown_safe = true;
}
}
return useful_pathkeys_list;
}
static void
sqlite_add_paths_with_pathkeys_for_rel(PlannerInfo *root, RelOptInfo *rel, List *fdw_private, Path *epq_path)
{
List *useful_pathkeys_list = NIL; /* List of all pathkeys */
ListCell *lc;
double rows;
Cost startup_cost;
Cost total_cost;
/* Use small cost to avoid calculating real cost size in SQLite */
rows = startup_cost = total_cost = 10;
useful_pathkeys_list = sqlite_get_useful_pathkeys_for_relation(root, rel);
#if PG_VERSION_NUM >= 150000
/*
* Before creating sorted paths, arrange for the passed-in EPQ path, if
* any, to return columns needed by the parent ForeignScan node so that
* they will propagate up through Sort nodes injected below, if necessary.
*/
if (epq_path != NULL && useful_pathkeys_list != NIL)
{
SqliteFdwRelationInfo *fpinfo = (SqliteFdwRelationInfo *) rel->fdw_private;
PathTarget *target = copy_pathtarget(epq_path->pathtarget);
/* Include columns required for evaluating PHVs in the tlist. */
add_new_columns_to_pathtarget(target,
pull_var_clause((Node *) target->exprs,
PVC_RECURSE_PLACEHOLDERS));
/* Include columns required for evaluating the local conditions. */
foreach(lc, fpinfo->local_conds)
{
RestrictInfo *rinfo = lfirst_node(RestrictInfo, lc);
add_new_columns_to_pathtarget(target,
pull_var_clause((Node *) rinfo->clause,
PVC_RECURSE_PLACEHOLDERS));
}
/*
* If we have added any new columns, adjust the tlist of the EPQ path.
*
* Note: the plan created using this path will only be used to execute
* EPQ checks, where accuracy of the plan cost and width estimates
* would not be important, so we do not do set_pathtarget_cost_width()
* for the new pathtarget here. See also postgresGetForeignPlan().
*/
if (list_length(target->exprs) > list_length(epq_path->pathtarget->exprs))
{
/* The EPQ path is a join path, so it is projection-capable. */
Assert(is_projection_capable_path(epq_path));
/*
* Use create_projection_path() here, so as to avoid modifying it
* in place.
*/
epq_path = (Path *) create_projection_path(root,
rel,
epq_path,
target);
}
}
#endif
/* Create one path for each set of pathkeys we found above. */
foreach(lc, useful_pathkeys_list)
{
List *useful_pathkeys = lfirst(lc);
Path *sorted_epq_path;
/*
* The EPQ path must be at least as well sorted as the path itself, in
* case it gets used as input to a mergejoin.
*/
sorted_epq_path = epq_path;
if (sorted_epq_path != NULL &&
!pathkeys_contained_in(useful_pathkeys,
sorted_epq_path->pathkeys))
sorted_epq_path = (Path *)
create_sort_path(root,
rel,
sorted_epq_path,
useful_pathkeys,
-1.0);
if (rel->reloptkind == RELOPT_BASEREL ||
rel->reloptkind == RELOPT_OTHER_MEMBER_REL)
add_path(rel, (Path *)
create_foreignscan_path(root, rel,
NULL,
rows,
startup_cost,
total_cost,
useful_pathkeys,
#if (PG_VERSION_NUM >= 120000)
rel->lateral_relids,
#else
NULL, /* no outer rel either */
#endif
sorted_epq_path,
fdw_private));
else
add_path(rel, (Path *)
#if PG_VERSION_NUM >= 120000
create_foreign_join_path(root, rel,
#else
create_foreignscan_path(root, rel,
#endif
NULL,
rows,
startup_cost,
total_cost,
useful_pathkeys,
#if (PG_VERSION_NUM >= 120000)
rel->lateral_relids,
#else
NULL, /* no outer rel either */
#endif
sorted_epq_path,
fdw_private));
}
}
/*
* Check if any of the tables queried aren't foreign tables.
* We use this function to add limit pushdownm fallback to sqlite
* because if theres any non-foreign table, GetForeignUpperPath its not called from planner.c
*/
static bool
sqlite_all_baserels_are_foreign(PlannerInfo *root)
{
bool allTablesQueriedAreForeign = true;
ListCell *l;
/*
* If there is no append_rel_list, we assume we're only consulting a
* foreign table, so default value it's true and we dont need to do more.
*/
foreach(l, root->append_rel_list)
{
AppendRelInfo *appinfo = lfirst_node(AppendRelInfo, l);
int childRTindex;
RangeTblEntry *childRTE;
RelOptInfo *childrel;
/* Re-locate the child RTE and RelOptInfo */
childRTindex = appinfo->child_relid;
childRTE = root->simple_rte_array[childRTindex];
childrel = root->simple_rel_array[childRTindex];
if (!(IS_DUMMY_REL(childrel) || childRTE->inh))
{
if (!(childrel->rtekind == RTE_RELATION && childRTE->relkind == RELKIND_FOREIGN_TABLE))
{
allTablesQueriedAreForeign = false;
break;
}
}
}
return allTablesQueriedAreForeign;
}
/*
* sqliteGetForeignPaths
* Create possible scan paths for a scan on the foreign table
*/
static void
sqliteGetForeignPaths(PlannerInfo *root, RelOptInfo *baserel, Oid foreigntableid)
{
SqliteFdwRelationInfo *fpinfo = (SqliteFdwRelationInfo *) baserel->fdw_private;
ForeignPath *path;
List *ppi_list;
ListCell *lc;
Cost startup_cost = 10;
Cost total_cost = baserel->rows + startup_cost;
List *fdw_private = NIL;
elog(DEBUG1, "sqlite_fdw : %s", __func__);
/* Estimate costs */
total_cost = baserel->rows;
/*
* We add fdw_private with has_limit: true if these three conditions are
* true because we need to be able to pushdown limit in this case: - Query
* has LIMIT - Query don't have OFFSET because if we pusdown OFFSET and
* later, we re-applying offset with the "final result", and we would be
* "jumping/skipping" child results and losing registries that we wanted
* to show. - Some of the baserels are not a foreign table, so PostgreSQL
* is not calling GetForeignUpperPaths
*/
if (limit_needed(root->parse) && !root->parse->limitOffset && !sqlite_all_baserels_are_foreign(root))
#if PG_VERSION_NUM >= 150000
fdw_private = list_make2(makeBoolean(false), makeBoolean(true));
#else
fdw_private = list_make2(makeInteger(false), makeInteger(true));
#endif
/* Create a ForeignPath node and add it as only possible path */
add_path(baserel, (Path *)
create_foreignscan_path(root, baserel,
#if PG_VERSION_NUM >= 90600
NULL, /* default pathtarget */
#endif
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 */
fdw_private));
/* Add paths with pathkeys */
sqlite_add_paths_with_pathkeys_for_rel(root, baserel, fdw_private, NULL);
/*
* If we're not using remote estimates, stop here. We have no way to
* estimate whether any join clauses would be worth sending across, so
* don't bother building parameterized paths.
*/
if (!fpinfo->use_remote_estimate)
return;
/*
* Thumb through all join clauses for the rel to identify which outer
* relations could supply one or more safe-to-send-to-remote join clauses.
* We'll build a parameterized path for each such outer relation.
*
* It's convenient to manage this by representing each candidate outer
* relation by the ParamPathInfo node for it. We can then use the
* ppi_clauses list in the ParamPathInfo node directly as a list of the
* interesting join clauses for that rel. This takes care of the
* possibility that there are multiple safe join clauses for such a rel,
* and also ensures that we account for unsafe join clauses that we'll
* still have to enforce locally (since the parameterized-path machinery
* insists that we handle all movable clauses).
*/
ppi_list = NIL;
foreach(lc, baserel->joininfo)
{
RestrictInfo *rinfo = (RestrictInfo *) lfirst(lc);
Relids required_outer;
ParamPathInfo *param_info;
/* Check if clause can be moved to this rel */
if (!join_clause_is_movable_to(rinfo, baserel))
continue;
/* See if it is safe to send to remote */
if (!sqlite_is_foreign_expr(root, baserel, rinfo->clause))
continue;