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mongo_fdw.c
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/*-------------------------------------------------------------------------
*
* mongo_fdw.c
* Foreign-data wrapper for remote MongoDB servers
*
* Portions Copyright (c) 2012-2014, PostgreSQL Global Development Group
* Portions Copyright (c) 2004-2024, EnterpriseDB Corporation.
* Portions Copyright (c) 2012–2014 Citus Data, Inc.
*
* IDENTIFICATION
* mongo_fdw.c
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "mongo_wrapper.h"
#include "access/htup_details.h"
#include "access/table.h"
#include "catalog/heap.h"
#include "catalog/pg_operator.h"
#include "catalog/pg_type.h"
#if PG_VERSION_NUM >= 130000
#include "common/hashfn.h"
#include "common/jsonapi.h"
#endif
#include "miscadmin.h"
#include "mongo_fdw.h"
#include "mongo_query.h"
#include "nodes/nodeFuncs.h"
#if PG_VERSION_NUM >= 140000
#include "optimizer/appendinfo.h"
#endif
#include "optimizer/optimizer.h"
#include "optimizer/paths.h"
#include "optimizer/tlist.h"
#include "parser/parsetree.h"
#if PG_VERSION_NUM >= 160000
#include "parser/parse_relation.h"
#endif
#include "storage/ipc.h"
#include "utils/guc.h"
#include "utils/jsonb.h"
#if PG_VERSION_NUM < 130000
#include "utils/jsonapi.h"
#else
#include "utils/jsonfuncs.h"
#endif
#include "utils/rel.h"
#include "utils/selfuncs.h"
#include "utils/syscache.h"
#include "utils/typcache.h"
/* Declarations for dynamic loading */
PG_MODULE_MAGIC;
/*
* In PG 9.5.1 the number will be 90501,
* our version is 5.5.2 so number will be 50502
*/
#define CODE_VERSION 50502
/*
* Macro to check unsupported sorting methods. Currently, ASC NULLS FIRST and
* DESC NULLS LAST give the same sorting result on MongoDB and Postgres. So,
* sorting methods other than these are not pushed down.
*/
#define IS_PATHKEY_PUSHABLE(pathkey) \
((pathkey->pk_strategy == BTLessStrategyNumber && pathkey->pk_nulls_first) || \
(pathkey->pk_strategy != BTLessStrategyNumber && !pathkey->pk_nulls_first))
/* Maximum path keys supported by MongoDB */
#define MAX_PATHKEYS 32
/*
* The number of rows in a foreign relation are estimated to be so less that
* an in-memory sort on those many rows wouldn't cost noticeably higher than
* the underlying scan. Hence for now, cost sorts same as underlying scans.
*/
#define DEFAULT_MONGO_SORT_MULTIPLIER 1
/* GUC variables. */
static bool enable_join_pushdown = true;
static bool enable_order_by_pushdown = true;
static bool enable_aggregate_pushdown = true;
/*
* 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
};
extern PGDLLEXPORT void _PG_init(void);
PG_FUNCTION_INFO_V1(mongo_fdw_handler);
PG_FUNCTION_INFO_V1(mongo_fdw_version);
/* FDW callback routines */
static void mongoGetForeignRelSize(PlannerInfo *root,
RelOptInfo *baserel,
Oid foreigntableid);
static void mongoGetForeignPaths(PlannerInfo *root,
RelOptInfo *baserel,
Oid foreigntableid);
static ForeignScan *mongoGetForeignPlan(PlannerInfo *root,
RelOptInfo *foreignrel,
Oid foreigntableid,
ForeignPath *best_path,
List *targetlist,
List *restrictionClauses,
Plan *outer_plan);
static void mongoExplainForeignScan(ForeignScanState *node, ExplainState *es);
static void mongoBeginForeignScan(ForeignScanState *node, int eflags);
static TupleTableSlot *mongoIterateForeignScan(ForeignScanState *node);
static void mongoEndForeignScan(ForeignScanState *node);
static void mongoReScanForeignScan(ForeignScanState *node);
static TupleTableSlot *mongoExecForeignUpdate(EState *estate,
ResultRelInfo *resultRelInfo,
TupleTableSlot *slot,
TupleTableSlot *planSlot);
static TupleTableSlot *mongoExecForeignDelete(EState *estate,
ResultRelInfo *resultRelInfo,
TupleTableSlot *slot,
TupleTableSlot *planSlot);
static void mongoEndForeignModify(EState *estate,
ResultRelInfo *resultRelInfo);
#if PG_VERSION_NUM >= 140000
static void mongoAddForeignUpdateTargets(PlannerInfo *root,
Index rtindex,
RangeTblEntry *target_rte,
Relation target_relation);
#else
static void mongoAddForeignUpdateTargets(Query *parsetree,
RangeTblEntry *target_rte,
Relation target_relation);
#endif
static void mongoBeginForeignModify(ModifyTableState *mtstate,
ResultRelInfo *resultRelInfo,
List *fdw_private,
int subplan_index,
int eflags);
static TupleTableSlot *mongoExecForeignInsert(EState *estate,
ResultRelInfo *resultRelInfo,
TupleTableSlot *slot,
TupleTableSlot *planSlot);
static List *mongoPlanForeignModify(PlannerInfo *root,
ModifyTable *plan,
Index resultRelation,
int subplan_index);
static void mongoExplainForeignModify(ModifyTableState *mtstate,
ResultRelInfo *rinfo,
List *fdw_private,
int subplan_index,
ExplainState *es);
static bool mongoAnalyzeForeignTable(Relation relation,
AcquireSampleRowsFunc *func,
BlockNumber *totalpages);
static void mongoBeginForeignInsert(ModifyTableState *mtstate,
ResultRelInfo *resultRelInfo);
static void mongoEndForeignInsert(EState *estate,
ResultRelInfo *resultRelInfo);
static void mongoGetForeignJoinPaths(PlannerInfo *root, RelOptInfo *joinrel,
RelOptInfo *outerrel,
RelOptInfo *innerrel,
JoinType jointype,
JoinPathExtraData *extra);
static void mongoGetForeignUpperPaths(PlannerInfo *root,
UpperRelationKind stage,
RelOptInfo *input_rel,
RelOptInfo *output_rel,
void *extra);
/*
* Helper functions
*/
static double foreign_table_document_count(Oid foreignTableId);
static HTAB *column_mapping_hash(Oid foreignTableId, List *columnList,
List *colNameList, List *colIsInnerList,
uint32 relType);
static void fill_tuple_slot(const BSON *bsonDocument,
const char *bsonDocumentKey,
HTAB *columnMappingHash,
Datum *columnValues,
bool *columnNulls,
uint32 relType);
static bool column_types_compatible(BSON_TYPE bsonType, Oid columnTypeId);
static Datum column_value_array(BSON_ITERATOR *bsonIterator, Oid valueTypeId);
static Datum column_value(BSON_ITERATOR *bsonIterator,
Oid columnTypeId,
int32 columnTypeMod);
static void mongo_free_scan_state(MongoFdwModifyState *fmstate);
static int mongo_acquire_sample_rows(Relation relation,
int errorLevel,
HeapTuple *sampleRows,
int targetRowCount,
double *totalRowCount,
double *totalDeadRowCount);
static void mongo_fdw_exit(int code, Datum arg);
static bool mongo_foreign_join_ok(PlannerInfo *root, RelOptInfo *joinrel,
JoinType jointype, RelOptInfo *outerrel,
RelOptInfo *innerrel,
JoinPathExtraData *extra);
static void mongo_prepare_qual_info(List *quals, MongoRelQualInfo *qual_info);
static bool mongo_foreign_grouping_ok(PlannerInfo *root,
RelOptInfo *grouped_rel,
Node *havingQual);
static void mongo_add_foreign_grouping_paths(PlannerInfo *root,
RelOptInfo *input_rel,
RelOptInfo *grouped_rel,
GroupPathExtraData *extra);
static void mongo_add_foreign_final_paths(PlannerInfo *root,
RelOptInfo *input_rel,
RelOptInfo *final_rel,
FinalPathExtraData *extra);
static void mongoEstimateCosts(RelOptInfo *baserel, Cost *startup_cost,
Cost *total_cost, Oid foreigntableid);
static List *mongo_get_useful_ecs_for_relation(PlannerInfo *root,
RelOptInfo *rel);
static List *mongo_get_useful_pathkeys_for_relation(PlannerInfo *root,
RelOptInfo *rel);
#if PG_VERSION_NUM >= 170000
static void mongo_add_paths_with_pathkeys(PlannerInfo *root,
RelOptInfo *rel,
Path *epq_path,
Cost base_startup_cost,
Cost base_total_cost,
List *restrictlist);
#else
static void mongo_add_paths_with_pathkeys(PlannerInfo *root,
RelOptInfo *rel,
Path *epq_path,
Cost base_startup_cost,
Cost base_total_cost);
#endif
static EquivalenceMember *mongo_find_em_for_rel_target(PlannerInfo *root,
EquivalenceClass *ec,
RelOptInfo *rel);
static void mongo_add_foreign_ordered_paths(PlannerInfo *root,
RelOptInfo *input_rel,
RelOptInfo *ordered_rel);
/* The null action object used for pure validation */
#if PG_VERSION_NUM < 130000
static JsonSemAction nullSemAction =
{
NULL, NULL, NULL, NULL, NULL,
NULL, NULL, NULL, NULL, NULL
};
#else
JsonSemAction nullSemAction =
{
NULL, NULL, NULL, NULL, NULL,
NULL, NULL, NULL, NULL, NULL
};
#endif
/*
* Library load-time initalization, sets on_proc_exit() callback for
* backend shutdown.
*/
void
_PG_init(void)
{
/*
* Sometimes getting a join or sorted result from MongoDB server is slower
* than performing those operations locally. To have that flexibility add
* a few GUCs to control those push-downs.
*/
DefineCustomBoolVariable("mongo_fdw.enable_join_pushdown",
"enable/disable join pushdown",
NULL,
&enable_join_pushdown,
true,
PGC_SUSET,
0,
NULL,
NULL,
NULL);
DefineCustomBoolVariable("mongo_fdw.enable_order_by_pushdown",
"Enable/Disable ORDER BY push down",
NULL,
&enable_order_by_pushdown,
true,
PGC_SUSET,
0,
NULL,
NULL,
NULL);
DefineCustomBoolVariable("mongo_fdw.enable_aggregate_pushdown",
"Enable/Disable aggregate push down",
NULL,
&enable_aggregate_pushdown,
true,
PGC_SUSET,
0,
NULL,
NULL,
NULL);
/* Initialize MongoDB C driver */
mongoc_init();
on_proc_exit(&mongo_fdw_exit, PointerGetDatum(NULL));
}
/*
* mongo_fdw_handler
* Creates and returns a struct with pointers to foreign table callback
* functions.
*/
Datum
mongo_fdw_handler(PG_FUNCTION_ARGS)
{
FdwRoutine *fdwRoutine = makeNode(FdwRoutine);
/* Functions for scanning foreign tables */
fdwRoutine->GetForeignRelSize = mongoGetForeignRelSize;
fdwRoutine->GetForeignPaths = mongoGetForeignPaths;
fdwRoutine->GetForeignPlan = mongoGetForeignPlan;
fdwRoutine->BeginForeignScan = mongoBeginForeignScan;
fdwRoutine->IterateForeignScan = mongoIterateForeignScan;
fdwRoutine->ReScanForeignScan = mongoReScanForeignScan;
fdwRoutine->EndForeignScan = mongoEndForeignScan;
/* Support for insert/update/delete */
fdwRoutine->AddForeignUpdateTargets = mongoAddForeignUpdateTargets;
fdwRoutine->PlanForeignModify = mongoPlanForeignModify;
fdwRoutine->BeginForeignModify = mongoBeginForeignModify;
fdwRoutine->ExecForeignInsert = mongoExecForeignInsert;
fdwRoutine->ExecForeignUpdate = mongoExecForeignUpdate;
fdwRoutine->ExecForeignDelete = mongoExecForeignDelete;
fdwRoutine->EndForeignModify = mongoEndForeignModify;
/* Support for EXPLAIN */
fdwRoutine->ExplainForeignScan = mongoExplainForeignScan;
fdwRoutine->ExplainForeignModify = mongoExplainForeignModify;
/* Support for ANALYZE */
fdwRoutine->AnalyzeForeignTable = mongoAnalyzeForeignTable;
/* Partition routing and/or COPY from */
fdwRoutine->BeginForeignInsert = mongoBeginForeignInsert;
fdwRoutine->EndForeignInsert = mongoEndForeignInsert;
/* Support function for join push-down */
fdwRoutine->GetForeignJoinPaths = mongoGetForeignJoinPaths;
/* Support functions for upper relation push-down */
fdwRoutine->GetForeignUpperPaths = mongoGetForeignUpperPaths;
PG_RETURN_POINTER(fdwRoutine);
}
/*
* mongo_fdw_exit
* Exit callback function.
*/
static void
mongo_fdw_exit(int code, Datum arg)
{
mongo_cleanup_connection();
/* Release all memory and other resources allocated by the driver */
mongoc_cleanup();
}
/*
* MongoGetForeignRelSize
* Obtains relation size estimates for mongo foreign table.
*/
static void
mongoGetForeignRelSize(PlannerInfo *root,
RelOptInfo *baserel,
Oid foreigntableid)
{
RangeTblEntry *rte = planner_rt_fetch(baserel->relid, root);
MongoFdwRelationInfo *fpinfo;
MongoFdwOptions *options;
ListCell *lc;
char *relname;
char *database;
char *refname;
/*
* We use MongoFdwRelationInfo to pass various information to subsequent
* functions.
*/
fpinfo = (MongoFdwRelationInfo *) palloc0(sizeof(MongoFdwRelationInfo));
baserel->fdw_private = (void *) fpinfo;
/*
* Identify which baserestrictinfo clauses can be sent to the remote
* server and which can't. Only the OpExpr clauses are sent to the remote
* server.
*/
foreach(lc, baserel->baserestrictinfo)
{
RestrictInfo *ri = (RestrictInfo *) lfirst(lc);
if (mongo_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);
}
/* Base foreign tables need to be pushed down always. */
fpinfo->pushdown_safe = true;
/* Fetch options */
options = mongo_get_options(foreigntableid);
/*
* Retrieve exact document count for remote collection if asked,
* otherwise, use default estimate in planning.
*/
if (options->use_remote_estimate)
{
double documentCount = foreign_table_document_count(foreigntableid);
if (documentCount > 0.0)
{
double rowSelectivity;
/*
* We estimate the number of rows returned after restriction
* qualifiers are applied. This will be more accurate if analyze
* is run on this relation.
*/
rowSelectivity = clauselist_selectivity(root,
baserel->baserestrictinfo,
0, JOIN_INNER, NULL);
baserel->rows = clamp_row_est(documentCount * rowSelectivity);
}
else
ereport(DEBUG1,
(errmsg("could not retrieve document count for collection"),
errhint("Falling back to default estimates in planning.")));
}
relname = options->collectionName;
database = options->svr_database;
fpinfo->base_relname = relname;
/*
* 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 the VERBOSE option is specified
* or not, so always schema-qualify the foreign table name.
*/
fpinfo->relation_name = makeStringInfo();
refname = rte->eref->aliasname;
appendStringInfo(fpinfo->relation_name, "%s.%s",
quote_identifier(database),
quote_identifier(relname));
if (*refname && strcmp(refname, relname) != 0)
appendStringInfo(fpinfo->relation_name, " %s",
quote_identifier(rte->eref->aliasname));
/* Also store the options in fpinfo for further use */
fpinfo->options = options;
/*
* Store aggregation enable/disable option in the fpinfo directly for
* further use. This flag can be useful when options are not accessible
* in the recursive cases.
*/
fpinfo->is_agg_scanrel_pushable = options->enable_aggregate_pushdown;
/* Set the flag is_order_by_pushable of the base relation */
fpinfo->is_order_by_pushable = options->enable_order_by_pushdown;
}
/*
* mongoGetForeignPaths
* Creates the only scan path used to execute the query.
*
* Note that MongoDB may decide to use an underlying index for this scan, but
* that decision isn't deterministic or visible to us. We therefore create a
* single table scan path.
*/
static void
mongoGetForeignPaths(PlannerInfo *root,
RelOptInfo *baserel,
Oid foreigntableid)
{
Path *foreignPath;
MongoFdwOptions *options;
Cost startupCost = 0;
Cost totalCost = 0;
/* Fetch options */
options = mongo_get_options(foreigntableid);
/*
* Retrieve exact document count for remote collection if asked,
* otherwise, use default estimate in planning.
*/
if (options->use_remote_estimate)
{
double documentCount = foreign_table_document_count(foreigntableid);
if (documentCount > 0.0)
{
MongoFdwRelationInfo *fpinfo = (MongoFdwRelationInfo *) baserel->fdw_private;
double tupleFilterCost = baserel->baserestrictcost.per_tuple;
double inputRowCount;
double documentSelectivity;
double foreignTableSize;
int32 documentWidth;
BlockNumber pageCount;
double totalDiskAccessCost;
double cpuCostPerDoc;
double cpuCostPerRow;
double totalCpuCost;
double connectionCost;
List *opExpressionList;
/*
* We estimate the number of rows returned after restriction
* qualifiers are applied by MongoDB.
*/
opExpressionList = fpinfo->remote_conds;
documentSelectivity = clauselist_selectivity(root,
opExpressionList, 0,
JOIN_INNER, NULL);
inputRowCount = clamp_row_est(documentCount * documentSelectivity);
/*
* We estimate disk costs assuming a sequential scan over the
* data. This is an inaccurate assumption as Mongo scatters the
* data over disk pages, and may rely on an index to retrieve the
* data. Still, this should at least give us a relative cost.
*/
documentWidth = get_relation_data_width(foreigntableid,
baserel->attr_widths);
foreignTableSize = documentCount * documentWidth;
pageCount = (BlockNumber) rint(foreignTableSize / BLCKSZ);
totalDiskAccessCost = seq_page_cost * pageCount;
/*
* The cost of processing a document returned by Mongo (input row)
* is 5x the cost of processing a regular row.
*/
cpuCostPerDoc = cpu_tuple_cost;
cpuCostPerRow = (cpu_tuple_cost * MONGO_TUPLE_COST_MULTIPLIER) + tupleFilterCost;
totalCpuCost = (cpuCostPerDoc * documentCount) + (cpuCostPerRow * inputRowCount);
connectionCost = MONGO_CONNECTION_COST_MULTIPLIER * seq_page_cost;
startupCost = baserel->baserestrictcost.startup + connectionCost;
totalCost = startupCost + totalDiskAccessCost + totalCpuCost;
}
else
ereport(DEBUG1,
(errmsg("could not retrieve document count for collection"),
errhint("Falling back to default estimates in planning.")));
}
else
{
/* Estimate default costs */
mongoEstimateCosts(baserel, &startupCost, &totalCost, foreigntableid);
}
/* Create a foreign path node */
#if PG_VERSION_NUM >= 170000
foreignPath = (Path *) create_foreignscan_path(root, baserel,
NULL, /* default pathtarget */
baserel->rows,
startupCost,
totalCost,
NIL, /* no pathkeys */
baserel->lateral_relids,
NULL, /* no extra plan */
NIL, /* no fdw_restrictinfo list */
NIL); /* no fdw_private data */
#else
foreignPath = (Path *) create_foreignscan_path(root, baserel,
NULL, /* default pathtarget */
baserel->rows,
startupCost,
totalCost,
NIL, /* no pathkeys */
baserel->lateral_relids,
NULL, /* no extra plan */
NIL); /* no fdw_private list */
#endif
/* Add foreign path as the only possible path */
add_path(baserel, foreignPath);
/* Add paths with pathkeys */
#if PG_VERSION_NUM >= 170000
mongo_add_paths_with_pathkeys(root, baserel, NULL, startupCost, totalCost,
NIL);
#else
mongo_add_paths_with_pathkeys(root, baserel, NULL, startupCost, totalCost);
#endif
}
/*
* mongoGetForeignPlan
* Creates a foreign scan plan node for scanning the MongoDB collection.
*
* Note that MongoDB may decide to use an underlying index for this
* scan, but that decision isn't deterministic or visible to us.
*/
static ForeignScan *
mongoGetForeignPlan(PlannerInfo *root,
RelOptInfo *foreignrel,
Oid foreigntableid,
ForeignPath *best_path,
List *targetList,
List *restrictionClauses,
Plan *outer_plan)
{
MongoFdwRelationInfo *fpinfo = (MongoFdwRelationInfo *) foreignrel->fdw_private;
Index scan_relid = foreignrel->relid;
ForeignScan *foreignScan;
List *fdw_private;
List *columnList;
List *scan_var_list;
ListCell *lc;
List *local_exprs = NIL;
List *remote_exprs = NIL;
List *fdw_scan_tlist = NIL;
List *column_name_list = NIL;
List *is_inner_column_list = NIL;
List *quals = NIL;
MongoFdwRelType mongofdwreltype;
MongoRelQualInfo *qual_info;
MongoFdwRelationInfo *ofpinfo = NULL;
List *pathKeyList = NIL;
List *isAscSortList = NIL;
bool has_final_sort = false;
bool has_limit = false;
int64 limit_value;
int64 offset_value;
/*
* Get FDW private data created by mongoGetForeignUpperPaths(), if any.
*/
if (best_path->fdw_private)
{
has_final_sort = intVal(list_nth(best_path->fdw_private,
FdwPathPrivateHasFinalSort));
has_limit = intVal(list_nth(best_path->fdw_private,
FdwPathPrivateHasLimit));
}
/* Set scan relation id */
if (IS_SIMPLE_REL(foreignrel))
scan_relid = foreignrel->relid;
else
{
/* Join/Upper relation - set scan_relid to 0. */
scan_relid = 0;
Assert(!restrictionClauses);
/* Extract local expressions from local conditions */
foreach(lc, fpinfo->local_conds)
{
RestrictInfo *rinfo = (RestrictInfo *) lfirst(lc);
Assert(IsA(rinfo, RestrictInfo));
local_exprs = lappend(local_exprs, rinfo->clause);
}
/* Extract remote expressions from remote conditions */
foreach(lc, fpinfo->remote_conds)
{
RestrictInfo *rinfo = (RestrictInfo *) lfirst(lc);
Assert(IsA(rinfo, RestrictInfo));
remote_exprs = lappend(remote_exprs, rinfo->clause);
}
}
if (IS_UPPER_REL(foreignrel))
scan_var_list = pull_var_clause((Node *) fpinfo->grouped_tlist,
PVC_RECURSE_AGGREGATES);
else
scan_var_list = pull_var_clause((Node *) foreignrel->reltarget->exprs,
PVC_RECURSE_PLACEHOLDERS);
/* System attributes are not allowed. */
foreach(lc, scan_var_list)
{
Var *var = lfirst(lc);
const FormData_pg_attribute *attr;
Assert(IsA(var, Var));
if (var->varattno >= 0)
continue;
attr = SystemAttributeDefinition(var->varattno);
ereport(ERROR,
(errcode(ERRCODE_FDW_COLUMN_NAME_NOT_FOUND),
errmsg("system attribute \"%s\" can't be fetched from remote relation",
attr->attname.data)));
}
/*
* Separate the restrictionClauses into those that can be executed
* remotely and those that can't. baserestrictinfo clauses that were
* previously determined to be safe or unsafe are shown in
* fpinfo->remote_conds and fpinfo->local_conds. Anything else in the
* restrictionClauses list will be a join clause, which we have to check
* for remote-safety. Only the OpExpr clauses are sent to the remote
* server.
*/
foreach(lc, restrictionClauses)
{
RestrictInfo *rinfo = (RestrictInfo *) lfirst(lc);
Assert(IsA(rinfo, RestrictInfo));
/* Ignore pseudoconstants, they are 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 (IsA(rinfo->clause, OpExpr) &&
mongo_is_foreign_expr(root, foreignrel, rinfo->clause, false))
remote_exprs = lappend(remote_exprs, rinfo->clause);
else
local_exprs = lappend(local_exprs, rinfo->clause);
}
/* Add local expression Var nodes to scan_var_list. */
scan_var_list = list_concat_unique(NIL, scan_var_list);
if (IS_UPPER_REL(foreignrel))
scan_var_list = list_concat_unique(scan_var_list,
pull_var_clause((Node *) local_exprs,
PVC_RECURSE_AGGREGATES));
else
scan_var_list = list_concat_unique(scan_var_list,
pull_var_clause((Node *) local_exprs,
PVC_RECURSE_PLACEHOLDERS));
if (IS_JOIN_REL(foreignrel))
{
/*
* For join relations, the planner needs a targetlist, which
* represents the output of the ForeignScan node.
*/
fdw_scan_tlist = add_to_flat_tlist(NIL, scan_var_list);
/*
* Ensure that the outer plan produces a tuple whose descriptor
* matches our scan tuple slot. Also, remove the local conditions
* from the outer plan's quals, lest they be evaluated twice, once by
* the local plan and once by the scan.
*/
if (outer_plan)
{
/*
* First, update the plan's qual list if possible. In some cases,
* the quals might be enforced below the topmost plan level, in
* which case we'll fail to remove them; it's not worth working
* harder than this.
*/
foreach(lc, local_exprs)
{
Node *qual = lfirst(lc);
outer_plan->qual = list_delete(outer_plan->qual, qual);
/*
* For an inner join, the local conditions of the foreign scan
* plan can be part of the joinquals as well. (They might
* also be in the mergequals or hashquals, but we can't touch
* those without breaking the plan.)
*/
if (IsA(outer_plan, NestLoop) ||
IsA(outer_plan, MergeJoin) ||
IsA(outer_plan, HashJoin))
{
Join *join_plan = (Join *) outer_plan;
if (join_plan->jointype == JOIN_INNER)
join_plan->joinqual = list_delete(join_plan->joinqual,
qual);
}
}
/*
* Now fix the subplan's tlist --- this might result in inserting
* a Result node atop the plan tree.
*/
outer_plan = change_plan_targetlist(outer_plan, fdw_scan_tlist,
best_path->path.parallel_safe);
}
}
else if (IS_UPPER_REL(foreignrel))
{
/*
* scan_var_list should have expressions and not TargetEntry nodes.
* However, grouped_tlist created has TLEs, and thus retrieve them
* into scan_var_list.
*/
scan_var_list = list_concat_unique(NIL,
get_tlist_exprs(fpinfo->grouped_tlist,
false));
/*
* The targetlist computed while assessing push-down safety represents
* the result we expect from the foreign server.
*/
fdw_scan_tlist = fpinfo->grouped_tlist;
local_exprs = extract_actual_clauses(fpinfo->local_conds, false);
}
/* Form column list required for query execution from scan_var_list. */
columnList = mongo_get_column_list(root, foreignrel, scan_var_list,
&column_name_list,
&is_inner_column_list);
/*
* Identify the relation type. We can have a simple base rel, join rel,
* upper rel, and upper rel with join rel inside. Find out that.
*/
if (IS_UPPER_REL(foreignrel) && IS_JOIN_REL(fpinfo->outerrel))
mongofdwreltype = UPPER_JOIN_REL;
else if (IS_UPPER_REL(foreignrel))
mongofdwreltype = UPPER_REL;
else if (IS_JOIN_REL(foreignrel))
mongofdwreltype = JOIN_REL;
else
mongofdwreltype = BASE_REL;
/*
* We use MongoRelQualInfo to pass various information related to joining
* quals and grouping target to fdw_private which is used to form
* equivalent MongoDB query during the execution phase.
*/
qual_info = (MongoRelQualInfo *) palloc(sizeof(MongoRelQualInfo));
qual_info->root = root;
qual_info->foreignRel = foreignrel;
qual_info->exprColHash = NULL;
qual_info->colNameList = NIL;
qual_info->colNumList = NIL;
qual_info->rtiList = NIL;
qual_info->isOuterList = NIL;
qual_info->is_having = false;
qual_info->is_agg_column = false;
qual_info->aggTypeList = NIL;
qual_info->aggColList = NIL;
qual_info->isHavingList = NIL;
/*
* Prepare separate lists of information. This information would be
* useful at the time of execution to prepare the MongoDB query.
*/
if (IS_JOIN_REL(foreignrel) || IS_UPPER_REL(foreignrel))
{
ofpinfo = (MongoFdwRelationInfo *) fpinfo->outerrel->fdw_private;
/*
* Save foreign relation and relid's of an outer relation involved in
* the join depending on the relation type.
*/
if (mongofdwreltype == UPPER_JOIN_REL)
{
/* For aggregation over join relation */
qual_info->foreignRel = fpinfo->outerrel;
qual_info->outerRelids = ofpinfo->outerrel->relids;
}
else if (mongofdwreltype == UPPER_REL)
{
/* For aggregation relation */
qual_info->foreignRel = fpinfo->outerrel;
qual_info->outerRelids = fpinfo->outerrel->relids;
}
else
{
Assert(mongofdwreltype == JOIN_REL);
qual_info->foreignRel = foreignrel;
qual_info->outerRelids = fpinfo->outerrel->relids;
}
/*
* Extract required data of columns involved in join clauses and
* append it into the various lists required to pass it to the
* executor.
*
* Check and extract data for outer relation and its join clauses in
* case of aggregation on top of the join operation.
*/
if (IS_JOIN_REL(foreignrel) && fpinfo->joinclauses)
mongo_prepare_qual_info(fpinfo->joinclauses, qual_info);
else if (IS_JOIN_REL(fpinfo->outerrel) && ofpinfo->joinclauses)
mongo_prepare_qual_info(ofpinfo->joinclauses, qual_info);
/*
* Extract required data of columns involved in the WHERE clause and
* append it into the various lists required to pass it to the
* executor.
*/
if (IS_JOIN_REL(foreignrel) && fpinfo->remote_conds)
mongo_prepare_qual_info(fpinfo->remote_conds, qual_info);
/* Gather required information of an upper relation */
if (IS_UPPER_REL(foreignrel))
{
/* Extract remote expressions from the remote conditions */
foreach(lc, ofpinfo->remote_conds)
{
RestrictInfo *rinfo = (RestrictInfo *) lfirst(lc);
Assert(IsA(rinfo, RestrictInfo));
quals = lappend(quals, rinfo->clause);
}
/* Extract WHERE clause column information */
mongo_prepare_qual_info(quals, qual_info);
/*
* Extract grouping target information i.e grouping operation and
* grouping clause.
*/
mongo_prepare_qual_info(scan_var_list, qual_info);
/* Extract HAVING clause information */
if (fpinfo->remote_conds)
{
qual_info->is_having = true;
mongo_prepare_qual_info(fpinfo->remote_conds, qual_info);
}
}
else
quals = remote_exprs;
}
else
{
quals = remote_exprs;
/* For baserel */
qual_info->foreignRel = foreignrel;
qual_info->outerRelids = NULL;
/*
* Extract required data of columns involved in WHERE clause of the
* simple relation.
*/
mongo_prepare_qual_info(quals, qual_info);
}
/*
* Check the ORDER BY clause, and if we found any useful pathkeys, then
* store the required information.
*/
foreach(lc, best_path->path.pathkeys)
{
EquivalenceMember *em;
PathKey *pathkey = lfirst(lc);
Expr *em_expr;
if (has_final_sort)
{
/*
* By construction, foreignrel is the input relation to the final
* sort.
*/
em = mongo_find_em_for_rel_target(root, pathkey->pk_eclass,
foreignrel);
}
else
em = mongo_find_em_for_rel(root, pathkey->pk_eclass,
qual_info->foreignRel);
/*
* We don't expect any error here; it would mean that shippability
* wasn't verified earlier. For the same reason, we don't recheck
* shippability of the sort operator.
*/
if (em == NULL)
elog(ERROR, "could not find pathkey item to sort");
/* Ignore binary-compatible relabeling */
em_expr = em->em_expr;
while (IsA(em_expr, RelabelType))
em_expr = ((RelabelType *) em_expr)->arg;