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mongo_query.c
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mongo_query.c
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/*-------------------------------------------------------------------------
*
* mongo_query.c
* FDW query handling for mongo_fdw
*
* Portions Copyright (c) 2012-2014, PostgreSQL Global Development Group
* Portions Copyright (c) 2004-2023, EnterpriseDB Corporation.
* Portions Copyright (c) 2012–2014 Citus Data, Inc.
*
* IDENTIFICATION
* mongo_query.c
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "mongo_wrapper.h"
#include <bson.h>
#include <json.h>
#if PG_VERSION_NUM < 120000
#include "access/sysattr.h"
#endif
#include "access/htup_details.h"
#if PG_VERSION_NUM >= 120000
#include "access/table.h"
#endif
#include "catalog/heap.h"
#include "catalog/pg_collation.h"
#include "catalog/pg_operator.h"
#if PG_VERSION_NUM >= 130000
#include "common/hashfn.h"
#endif
#ifdef META_DRIVER
#include "mongoc.h"
#else
#include "mongo.h"
#endif
#include "mongo_query.h"
#if PG_VERSION_NUM < 120000
#include "nodes/relation.h"
#include "optimizer/var.h"
#endif
#if PG_VERSION_NUM >= 120000
#include "optimizer/optimizer.h"
#endif
#include "parser/parsetree.h"
#include "utils/rel.h"
#include "utils/syscache.h"
/*
* Global context for foreign_expr_walker's search of an expression tree.
*/
typedef struct foreign_glob_cxt
{
PlannerInfo *root; /* global planner state */
RelOptInfo *foreignrel; /* the foreign relation we are planning for */
#ifndef META_DRIVER
unsigned short varcount; /* Var count */
unsigned short opexprcount;
#endif
Relids relids; /* relids of base relations in the underlying
* scan */
bool is_having_cond; /* "true" for HAVING clause condition */
} foreign_glob_cxt;
/*
* Local (per-tree-level) context for foreign_expr_walker's search.
* This is concerned with identifying collations used in the expression.
*/
typedef enum
{
FDW_COLLATE_NONE, /* expression is of a noncollatable type */
FDW_COLLATE_SAFE, /* collation derives from a foreign Var */
FDW_COLLATE_UNSAFE /* collation derives from something else */
} FDWCollateState;
typedef struct foreign_loc_cxt
{
Oid collation; /* OID of current collation, if any */
FDWCollateState state; /* state of current collation choice */
} foreign_loc_cxt;
/* Local functions forward declarations */
#ifndef META_DRIVER
static Expr *find_argument_of_type(List *argumentList, NodeTag argumentType);
static List *equality_operator_list(List *operatorList);
static List *unique_column_list(List *operatorList);
static List *column_operator_list(Var *column, List *operatorList);
#endif
static bool foreign_expr_walker(Node *node,
foreign_glob_cxt *glob_cxt,
foreign_loc_cxt *outer_cxt);
static List *prepare_var_list_for_baserel(Oid relid, Index varno,
Bitmapset *attrs_used);
#ifdef META_DRIVER
static HTAB *column_info_hash(List *colname_list, List *colnum_list,
List *rti_list, List *isouter_list);
static void mongo_prepare_pipeline(List *clause, BSON *inner_pipeline,
pipeline_cxt *context);
static void mongo_append_clauses_to_pipeline(List *clause, BSON *child_doc,
pipeline_cxt *context);
#endif
#if PG_VERSION_NUM >= 160000
static List *mongo_append_unique_var(List *varlist, Var *var);
#endif
#ifndef META_DRIVER
/*
* find_argument_of_type
* Walks over the given argument list, looks for an argument with the
* given type, and returns the argument if it is found.
*/
static Expr *
find_argument_of_type(List *argumentList, NodeTag argumentType)
{
Expr *foundArgument = NULL;
ListCell *argumentCell;
foreach(argumentCell, argumentList)
{
Expr *argument = (Expr *) lfirst(argumentCell);
/* For RelabelType type, examine the inner node */
if (IsA(argument, RelabelType))
argument = ((RelabelType *) argument)->arg;
if (nodeTag(argument) == argumentType)
{
foundArgument = argument;
break;
}
}
return foundArgument;
}
#endif
/*
* mongo_query_document
* Takes in the applicable operator expressions for relation, the join
* clauses for join relation, and grouping targets for upper relation and
* converts these expressions, join clauses, and grouping targets into
* equivalent queries in MongoDB.
*
* For join clauses, transforms simple comparison expressions along with a
* comparison between two vars and nested operator expressions as well.
*
* Example: Consider the following two foreign tables:
* t1(_id NAME, age INT, name VARCHAR)
* t2(_id NAME, old INT, alias VARCHAR)
*
* SQL query:
* SELECT * FROM t1 LEFT JOIN t2 ON (t1.age = t2.old)
* WHERE (t1.age % 2) = 1
* ORDER BY t1.age ASC NULLS FIRST;
* Equivalent MongoDB query:
*
* db.t1.aggregate([
* {
* "$lookup":
* {
* "from": "t2",
* "let": { "v_age": "$age" },
* "pipeline": [
* {
* "$match":
* {
* "$expr":
* {
* "$and": [
* { "$eq": [ "$$v_age", "$old" ] }
* { "$ne": [ "$$v_age", null ] },
* { "$ne": [ "$old", null ] },
* ]
* }
* }
* }
* ],
* "as": "Join_Result"
* }
* },
* { "$match" :
* {
* "$expr" :
* { "$and" : [
* { "$eq" : [ { "$mod" : [ "$age", 2] }, 1]},
* { "$ne" : [ "$age", null ] }
* ]
* }
* }
* }
* {
* "$unwind":
* {
* "path": "$Join_Result",
* "preserveNullAndEmptyArrays": true
* }
* },
* { "$sort": { "age" : 1 } }
* ])
*
* Any MongoDB query would have the following three main arrays:
* 1. Root pipeline array (first square bracket):
* This has three elements called $lookup, $unwind, and $match stages.
* 2. Inner pipeline array (starting with "pipeline" keyword above):
* It has one element that is $match.
* 3. "$and" expression inside inner pipeline:
* These elements depend on the join clauses available.
*
* The outer $match stage (2nd element of root pipeline array) represents
* remote_exprs, and $match inside $lookup stage represents the join clauses.
*
* For grouping target, add $group stage on the base relation or join relation.
* The HAVING clause is nothing but a post $match stage.
*
* Example: Consider above table t1:
*
* SQL query:
* SELECT name, SUM(age) FROM t1 GROUP BY name HAVING MIN(name) = 'xyz'
* ORDER BY name DESC NULLS LAST;
*
* Equivalent MongoDB query:
*
* db.t1.aggregate([
* {
* "$group":
* {
* "_id": {"name": "$name"},
* "v_agg0": {"$sum": "$age"},
* "v_having": {"$min": "$name"}
* }
* },
* {
* "$match": {"v_having": "xyz"}
* }
* { "$sort": { "name" : -1 } }
* ])
*
* For ORDER BY, add $sort stage on the base relation or join or grouping
* relation as shown in the above examples of join and grouping relations.
*/
BSON *
mongo_query_document(ForeignScanState *scanStateNode)
{
ForeignScan *fsplan = (ForeignScan *) scanStateNode->ss.ps.plan;
BSON *queryDocument = bsonCreate();
BSON *filter = bsonCreate();
List *PrivateList = fsplan->fdw_private;
List *opExpressionList = list_nth(PrivateList,
mongoFdwPrivateRemoteExprList);
#ifdef META_DRIVER
MongoFdwModifyState *fmstate = (MongoFdwModifyState *) scanStateNode->fdw_state;
BSON root_pipeline;
BSON match_stage;
int root_index = 0;
List *joinclauses;
List *colnum_list;
List *colname_list = NIL;
List *isouter_list = NIL;
List *rti_list;
List *pathkey_list;
List *is_ascsort_list;
char *inner_relname;
char *outer_relname;
HTAB *columnInfoHash;
int jointype;
int natts;
bool has_limit;
/* Retrieve data passed by planning phase */
colname_list = list_nth(PrivateList, mongoFdwPrivateJoinClauseColNameList);
colnum_list = list_nth(PrivateList, mongoFdwPrivareJoinClauseColNumList);
rti_list = list_nth(PrivateList, mongoFdwPrivateJoinClauseRtiList);
isouter_list = list_nth(PrivateList, mongoFdwPrivateJoinClauseIsOuterList);
/* Length should be same for all lists of column information */
natts = list_length(colname_list);
Assert(natts == list_length(colnum_list) && natts == list_length(rti_list)
&& natts == list_length(isouter_list));
/* Store information in the hash-table */
columnInfoHash = column_info_hash(colname_list, colnum_list, rti_list,
isouter_list);
/* Retrieve information related to ORDER BY clause */
pathkey_list = list_nth(PrivateList, mongoFdwPrivatePathKeyList);
is_ascsort_list = list_nth(PrivateList, mongoFdwPrivateIsAscSortList);
/* Retrieve information related to LIMIT/OFFSET clause */
has_limit = intVal(list_nth(PrivateList, mongoFdwPrivateHasLimitClause));
if (fmstate->relType == JOIN_REL || fmstate->relType == UPPER_JOIN_REL)
{
List *innerouter_relname;
joinclauses = list_nth(PrivateList, mongoFdwPrivateJoinClauseList);
if (joinclauses)
jointype = intVal(list_nth(PrivateList, mongoFdwPrivateJoinType));
innerouter_relname = list_nth(PrivateList,
mongoFdwPrivateJoinInnerOuterRelName);
inner_relname = strVal(list_nth(innerouter_relname, 0));
outer_relname = strVal(list_nth(innerouter_relname, 1));
}
/* Prepare array of stages */
bsonAppendStartArray(queryDocument, "pipeline", &root_pipeline);
#endif
/*
* Add filter into query pipeline if available. These are remote_exprs
* i.e. clauses available in WHERE and those are push-able to the remote
* side.
*/
if (opExpressionList)
{
#ifdef META_DRIVER
pipeline_cxt context;
context.colInfoHash = columnInfoHash;
context.isBoolExpr = false;
context.isJoinClause = false;
context.scanStateNode = scanStateNode;
bsonAppendStartArray(filter, "pipeline", &match_stage);
/* Form equivalent WHERE clauses in MongoDB */
mongo_prepare_pipeline(opExpressionList, &match_stage, &context);
bsonAppendFinishArray(filter, &match_stage);
#else
Oid relationId;
List *equalityOperatorList;
List *comparisonOperatorList;
List *columnList;
ListCell *equalityOperatorCell;
ListCell *columnCell;
if (fsplan->scan.scanrelid > 0)
relationId = RelationGetRelid(scanStateNode->ss.ss_currentRelation);
else
relationId = 0;
/*
* We distinguish between equality expressions and others since we
* need to insert the latter (<, >, <=, >=, <>) as separate
* sub-documents into the BSON query object.
*/
equalityOperatorList = equality_operator_list(opExpressionList);
comparisonOperatorList = list_difference(opExpressionList,
equalityOperatorList);
/* Append equality expressions to the query */
foreach(equalityOperatorCell, equalityOperatorList)
{
OpExpr *equalityOperator;
Oid columnId = InvalidOid;
char *columnName;
Const *constant;
Param *paramNode;
List *argumentList;
Var *column;
equalityOperator = (OpExpr *) lfirst(equalityOperatorCell);
argumentList = equalityOperator->args;
column = (Var *) find_argument_of_type(argumentList, T_Var);
constant = (Const *) find_argument_of_type(argumentList, T_Const);
paramNode = (Param *) find_argument_of_type(argumentList, T_Param);
columnId = column->varattno;
columnName = get_attname(relationId, columnId, false);
if (constant != NULL)
append_constant_value(filter, columnName, constant);
else
append_param_value(filter, columnName, paramNode,
scanStateNode);
}
/*
* For comparison expressions, we need to group them by their columns
* and then append all expressions that correspond to a column as one
* sub-document. Otherwise, even when we have two expressions to
* define the upper and lower bound of a range, Mongo uses only one of
* these expressions during an index search.
*/
columnList = unique_column_list(comparisonOperatorList);
/* Append comparison expressions, grouped by columns, to the query */
foreach(columnCell, columnList)
{
Var *column = (Var *) lfirst(columnCell);
Oid columnId = InvalidOid;
char *columnName;
List *columnOperatorList;
ListCell *columnOperatorCell;
BSON childDocument;
if (relationId != 0)
{
columnId = column->varattno;
columnName = get_attname(relationId, columnId, false);
}
/* Find all expressions that correspond to the column */
columnOperatorList = column_operator_list(column,
comparisonOperatorList);
/* For comparison expressions, start a sub-document */
bsonAppendStartObject(filter, columnName, &childDocument);
foreach(columnOperatorCell, columnOperatorList)
{
OpExpr *columnOperator;
char *operatorName;
char *mongoOperatorName;
List *argumentList;
Const *constant;
Param *paramNode;
columnOperator = (OpExpr *) lfirst(columnOperatorCell);
argumentList = columnOperator->args;
constant = (Const *) find_argument_of_type(argumentList,
T_Const);
paramNode = (Param *) find_argument_of_type(argumentList,
T_Param);
operatorName = get_opname(columnOperator->opno);
mongoOperatorName = mongo_operator_name(operatorName);
if (constant != NULL)
append_constant_value(filter, mongoOperatorName, constant);
else
append_param_value(filter, mongoOperatorName, paramNode,
scanStateNode);
}
bsonAppendFinishObject(filter, &childDocument);
}
#endif
}
if (!bsonFinish(filter))
{
#ifdef META_DRIVER
ereport(ERROR,
(errmsg("could not create document for query"),
errhint("BSON flags: %d", queryDocument->flags)));
#else
ereport(ERROR,
(errmsg("could not create document for query"),
errhint("BSON error: %d", queryDocument->err)));
#endif
}
#ifdef META_DRIVER
if (fmstate->relType == JOIN_REL || fmstate->relType == UPPER_JOIN_REL)
{
BSON inner_pipeline;
BSON lookup_object;
BSON lookup;
BSON let_exprs;
BSON unwind_stage;
BSON unwind;
BSON *inner_pipeline_doc = bsonCreate();
ListCell *cell1;
ListCell *cell2;
/* $lookup stage. This is to perform JOIN */
bsonAppendStartObject(&root_pipeline, psprintf("%d", root_index++),
&lookup_object);
bsonAppendStartObject(&lookup_object, "$lookup", &lookup);
bsonAppendUTF8(&lookup, "from", inner_relname);
/*
* Start "let" operator: Specifies variables to use in the pipeline
* stages. To access columns of outer relation, those need to be
* defined in terms of a variable using "let".
*/
bsonAppendStartObject(&lookup, "let", &let_exprs);
forboth(cell1, colname_list, cell2, isouter_list)
{
char *colname = strVal(lfirst(cell1));
bool is_outer = lfirst_int(cell2);
/*
* Ignore column name with "*" because this is not the name of any
* particular column and is not allowed in the let operator. While
* deparsing the COUNT(*) aggregation operation, this column name
* is added to lists to maintain the length of column information.
*/
if (is_outer && strcmp(colname, "*") != 0)
{
/*
* Add prefix "v_" to column name to form variable name. Need
* to prefix with any lowercase letter because variable names
* must begin with only a lowercase ASCII letter or a
* non-ASCII character.
*/
char *varname = psprintf("v_%s", colname);
char *field = psprintf("$%s", colname);
bsonAppendUTF8(&let_exprs, varname, field);
}
}
bsonAppendFinishObject(&lookup, &let_exprs); /* End "let" */
/* Form inner pipeline required in $lookup stage to execute $match */
bsonAppendStartArray(inner_pipeline_doc, "pipeline", &inner_pipeline);
if (joinclauses)
{
pipeline_cxt context;
context.colInfoHash = columnInfoHash;
context.isBoolExpr = false;
context.isJoinClause = true;
context.scanStateNode = scanStateNode;
/* Form equivalent join qual clauses in MongoDB */
mongo_prepare_pipeline(joinclauses, &inner_pipeline, &context);
bsonAppendFinishArray(inner_pipeline_doc, &inner_pipeline);
}
/* Append inner pipeline to $lookup stage */
bson_append_array(&lookup, "pipeline", (int) strlen("pipeline"),
&inner_pipeline);
bsonAppendUTF8(&lookup, "as", "Join_Result");
bsonAppendFinishObject(&lookup_object, &lookup);
bsonAppendFinishObject(&root_pipeline, &lookup_object);
/* $match stage. This is to add a filter */
if (opExpressionList)
bsonAppendBson(&root_pipeline, "$match", &match_stage);
/*
* $unwind stage. This deconstructs an array field from the input
* documents to output a document for each element.
*/
bsonAppendStartObject(&root_pipeline, psprintf("%d", root_index++),
&unwind_stage);
bsonAppendStartObject(&unwind_stage, "$unwind", &unwind);
bsonAppendUTF8(&unwind, "path", "$Join_Result");
if (jointype == JOIN_INNER)
bsonAppendBool(&unwind, "preserveNullAndEmptyArrays", false);
else
bsonAppendBool(&unwind, "preserveNullAndEmptyArrays", true);
bsonAppendFinishObject(&unwind_stage, &unwind);
bsonAppendFinishObject(&root_pipeline, &unwind_stage);
fmstate->outerRelName = outer_relname;
}
else if (opExpressionList)
bsonAppendBson(&root_pipeline, "$match", &match_stage);
/* Add $group stage for upper relation */
if (fmstate->relType == UPPER_JOIN_REL || fmstate->relType == UPPER_REL)
{
List *func_list;
List *agg_col_list;
List *groupby_col_list;
List *having_expr;
BSON groupby_expr;
BSON group_stage;
BSON group_expr;
BSON group;
ListCell *cell1;
ListCell *cell2;
ListCell *cell3;
List *is_having_list;
Index aggIndex = 0;
func_list = list_nth(PrivateList, mongoFdwPrivateAggType);
agg_col_list = list_nth(PrivateList, mongoFdwPrivateAggColList);
groupby_col_list = list_nth(PrivateList, mongoFdwPrivateGroupByColList);
having_expr = list_nth(PrivateList, mongoFdwPrivateHavingExpr);
is_having_list = list_nth(PrivateList, mongoFdwPrivateIsHavingList);
/* $group stage. */
bsonAppendStartObject(&root_pipeline, psprintf("%d", root_index++),
&group_stage);
bsonAppendStartObject(&group_stage, "$group", &group);
/*
* Add columns from the GROUP BY clause in the "_id" field of $group
* stage. In case of aggregation on join result, a column of the
* inner table needs to be accessed by prefixing it using
* "Join_Result", which is been hardcoded.
*/
if (groupby_col_list)
{
ListCell *columnCell;
bsonAppendStartObject(&group, "_id", &groupby_expr);
foreach(columnCell, groupby_col_list)
{
Var *column = (Var *) lfirst(columnCell);
bool found = false;
ColInfoHashKey key;
ColInfoHashEntry *columnInfo;
key.varNo = column->varno;
key.varAttno = column->varattno;
columnInfo = (ColInfoHashEntry *) hash_search(columnInfoHash,
(void *) &key,
HASH_FIND,
&found);
if (found)
{
if (columnInfo->isOuter)
bsonAppendUTF8(&groupby_expr, columnInfo->colName,
psprintf("$%s", columnInfo->colName));
else
bsonAppendUTF8(&groupby_expr, columnInfo->colName,
psprintf("$Join_Result.%s",
columnInfo->colName));
}
}
bsonAppendFinishObject(&group, &groupby_expr); /* End "_id" */
}
else
{
/* If no GROUP BY clause then append null to the _id. */
bsonAppendNull(&group, "_id");
}
/* Add grouping operation */
forthree(cell1, func_list, cell2, agg_col_list, cell3, is_having_list)
{
ColInfoHashKey key;
ColInfoHashEntry *columnInfo;
bool found = false;
char *func_name = strVal(lfirst(cell1));
Var *column = (Var *) lfirst(cell2);
bool is_having_agg = lfirst_int(cell3);
if (is_having_agg)
bsonAppendStartObject(&group, "v_having", &group_expr);
else
bsonAppendStartObject(&group,
psprintf("AGG_RESULT_KEY%d",
aggIndex++),
&group_expr);
key.varNo = column->varno;
key.varAttno = column->varattno;
columnInfo = (ColInfoHashEntry *) hash_search(columnInfoHash,
(void *) &key,
HASH_FIND,
&found);
/*
* The aggregation operation in MongoDB other than COUNT has the
* same name as PostgreSQL but COUNT needs to be performed using
* the $sum operator because MongoDB doesn't have a direct $count
* operator for the currently supported version (i.e. v4.4).
*
* There is no syntax in MongoDB to provide column names for COUNT
* operation but for other supported operations, we can do so.
*
* In case of aggregation over the join, the resulted columns of
* inner relation need to be accessed by prefixing it with
* "Join_Result".
*/
if (found && strcmp(func_name, "count") != 0)
{
if (columnInfo->isOuter)
bsonAppendUTF8(&group_expr, psprintf("$%s", func_name),
psprintf("$%s", columnInfo->colName));
else
bsonAppendUTF8(&group_expr, psprintf("$%s", func_name),
psprintf("$Join_Result.%s",
columnInfo->colName));
}
else
{
/*
* The COUNT(*) in PostgreSQL is equivalent to {$sum: 1} in
* the MongoDB.
*/
bsonAppendInt32(&group_expr, psprintf("$%s", "sum"), 1);
}
bsonAppendFinishObject(&group, &group_expr);
}
bsonAppendFinishObject(&group_stage, &group);
bsonAppendFinishObject(&root_pipeline, &group_stage);
/* Add HAVING operation */
if (having_expr)
{
pipeline_cxt context;
context.colInfoHash = columnInfoHash;
context.isBoolExpr = false;
context.isJoinClause = false;
context.scanStateNode = scanStateNode;
/* $match stage. Add a filter for the HAVING clause */
bsonAppendStartObject(&root_pipeline, psprintf("%d", root_index++),
&match_stage);
/* Form equivalent HAVING clauses in MongoDB */
mongo_prepare_pipeline(having_expr, &match_stage, &context);
bsonAppendFinishObject(&root_pipeline, &match_stage);
if (!bsonFinish(filter))
ereport(ERROR,
(errmsg("could not create document for query"),
errhint("BSON flags: %d", queryDocument->flags)));
}
}
/* Add sort stage */
if (pathkey_list)
{
BSON sort_stage;
BSON sort;
ListCell *cell1;
ListCell *cell2;
bsonAppendStartObject(&root_pipeline, psprintf("%d", root_index++),
&sort_stage);
bsonAppendStartObject(&sort_stage, "$sort", &sort);
forboth(cell1, pathkey_list, cell2, is_ascsort_list)
{
Var *column = (Var *) lfirst(cell1);
int is_asc_sort = lfirst_int(cell2);
bool found = false;
ColInfoHashKey key;
ColInfoHashEntry *columnInfo;
/* Find column name */
key.varNo = column->varno;
key.varAttno = column->varattno;
columnInfo = (ColInfoHashEntry *) hash_search(columnInfoHash,
(void *) &key,
HASH_FIND,
&found);
if (found)
{
/*
* In the case of upper rel, access the column by prefixing it
* with "_id". To access the column of the inner relation in
* the join operation, use the prefix "Join_result" because
* direct access is not possible. However, columns of the
* simple relation and outer relation of the join can be
* accessed directly.
*/
if (fmstate->relType == UPPER_JOIN_REL ||
fmstate->relType == UPPER_REL)
bsonAppendInt32(&sort,
psprintf("_id.%s", columnInfo->colName),
is_asc_sort);
else if (!columnInfo->isOuter && fmstate->relType != BASE_REL)
bsonAppendInt32(&sort,
psprintf("Join_result.%s",
columnInfo->colName),
is_asc_sort);
else
bsonAppendInt32(&sort, columnInfo->colName, is_asc_sort);
}
}
bsonAppendFinishObject(&sort_stage, &sort);
bsonAppendFinishObject(&root_pipeline, &sort_stage); /* End sort */
}
/* Add LIMIT/SKIP stage */
if (has_limit)
{
int64 limit_value;
int64 offset_value;
/*
* Add skip stage for OFFSET clause. However, don't add the same if
* either offset is not provided or the offset value is zero.
*/
offset_value = (int64) intVal(list_nth(PrivateList,
mongoFdwPrivateLimitOffsetList));
if (offset_value != -1 && offset_value != 0)
{
BSON skip_stage;
bsonAppendStartObject(&root_pipeline, psprintf("%d", root_index++),
&skip_stage);
bsonAppendInt64(&skip_stage, "$skip", offset_value);
bsonAppendFinishObject(&root_pipeline, &skip_stage);
}
/*
* Add limit stage for LIMIT clause. However, don't add the same if
* the limit is not provided.
*/
limit_value = (int64) intVal(list_nth(PrivateList,
mongoFdwPrivateLimitCountList));
if (limit_value != -1)
{
BSON limit_stage;
bsonAppendStartObject(&root_pipeline, psprintf("%d", root_index++),
&limit_stage);
bsonAppendInt64(&limit_stage, "$limit", limit_value);
bsonAppendFinishObject(&root_pipeline, &limit_stage);
}
}
bsonAppendFinishArray(queryDocument, &root_pipeline);
if (!bsonFinish(queryDocument))
{
ereport(ERROR,
(errmsg("could not create document for query"),
errhint("BSON flags: %d", queryDocument->flags)));
}
return queryDocument;
#endif
return filter;
}
/*
* mongo_operator_name
* Takes in the given PostgreSQL comparison operator name, and returns its
* equivalent in MongoDB.
*/
char *
mongo_operator_name(const char *operatorName)
{
const char *mongoOperatorName = NULL;
const int32 nameCount = 14;
static const char *nameMappings[][2] = {{"<", "$lt"},
{">", "$gt"},
{"<=", "$lte"},
{">=", "$gte"},
{"<>", "$ne"},
{"=", "$eq"},
{"+", "$add"},
{"-", "$subtract"},
{"*", "$multiply"},
{"/", "$divide"},
{"%", "$mod"},
{"^", "$pow"},
{"|/", "$sqrt"},
{"@", "$abs"}};
int32 nameIndex;
for (nameIndex = 0; nameIndex < nameCount; nameIndex++)
{
const char *pgOperatorName = nameMappings[nameIndex][0];
if (strncmp(pgOperatorName, operatorName, NAMEDATALEN) == 0)
{
mongoOperatorName = nameMappings[nameIndex][1];
break;
}
}
return (char *) mongoOperatorName;
}
#ifndef META_DRIVER
/*
* equality_operator_list
* Finds the equality (=) operators in the given list, and returns these
* operators in a new list.
*/
static List *
equality_operator_list(List *operatorList)
{
List *equalityOperatorList = NIL;
ListCell *operatorCell;
foreach(operatorCell, operatorList)
{
OpExpr *operator = (OpExpr *) lfirst(operatorCell);
if (strncmp(get_opname(operator->opno), EQUALITY_OPERATOR_NAME,
NAMEDATALEN) == 0)
equalityOperatorList = lappend(equalityOperatorList, operator);
}
return equalityOperatorList;
}
/*
* unique_column_list
* Walks over the given operator list, and extracts the column argument in
* each operator.
*
* The function then de-duplicates extracted columns, and returns them in a new
* list.
*/
static List *
unique_column_list(List *operatorList)
{
List *uniqueColumnList = NIL;
ListCell *operatorCell;
foreach(operatorCell, operatorList)
{
OpExpr *operator = (OpExpr *) lfirst(operatorCell);
List *argumentList = operator->args;
Var *column = (Var *) find_argument_of_type(argumentList,
T_Var);
#if PG_VERSION_NUM >= 160000
uniqueColumnList = mongo_append_unique_var(uniqueColumnList, column);
#else
/* List membership is determined via column's equal() function */
uniqueColumnList = list_append_unique(uniqueColumnList, column);
#endif
}
return uniqueColumnList;
}
/*
* column_operator_list
* Finds all expressions that correspond to the given column, and returns
* them in a new list.
*/
static List *
column_operator_list(Var *column, List *operatorList)
{
List *columnOperatorList = NIL;
ListCell *operatorCell;
foreach(operatorCell, operatorList)
{
OpExpr *operator = (OpExpr *) lfirst(operatorCell);
List *argumentList = operator->args;
Var *foundColumn = (Var *) find_argument_of_type(argumentList,
T_Var);
if (equal(column, foundColumn))
columnOperatorList = lappend(columnOperatorList, operator);
}
return columnOperatorList;
}
#endif
void
append_param_value(BSON *queryDocument, const char *keyName, Param *paramNode,
ForeignScanState *scanStateNode)
{
ExprState *param_expr;
Datum param_value;
bool isNull;
ExprContext *econtext;
if (scanStateNode == NULL)
return;
econtext = scanStateNode->ss.ps.ps_ExprContext;
/* Prepare for parameter expression evaluation */
param_expr = ExecInitExpr((Expr *) paramNode, (PlanState *) scanStateNode);
/* Evaluate the parameter expression */
param_value = ExecEvalExpr(param_expr, econtext, &isNull);
append_mongo_value(queryDocument, keyName, param_value, isNull,
paramNode->paramtype);
}
/*
* append_constant_value
* Appends to the query document the key name and constant value.
*
* The function translates the constant value from its PostgreSQL type
* to its MongoDB equivalent.
*/
void
append_constant_value(BSON *queryDocument, const char *keyName, Const *constant)
{
if (constant->constisnull)
{
bsonAppendNull(queryDocument, keyName);
return;
}
append_mongo_value(queryDocument, keyName, constant->constvalue, false,
constant->consttype);
}
bool
append_mongo_value(BSON *queryDocument, const char *keyName, Datum value,
bool isnull, Oid id)
{
bool status = false;
if (isnull)