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System Variables
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Overview
BI Connector provides the following environment variables:
System Variable | Data Type | Description | Default Value (Atlas-hosted) | Default Value (On Premises) |
|---|---|---|---|---|
full_pushdown_exec_mode | boolean | Specifies whether a query error is returned for queries with
clauses that aren't fully translated to the MongoDB query language.
SQL query predicates are used to filter data returned by the query. | 0 (false) | 0 (false) |
log_level | integer | Specifies the logging level for BI Connector:
| 2 (Atlas-hosted) and 0 (self-managed) | |
max_nested_table_depth | integer | Specifies the maximum number of unique nested field paths that
mongosqld maps to a relational table for a collection. | 50 | 50 |
max_num_columns_per_table | integer | The maximum number of unique fields that mongosqld maps to
relational columns for a collection. | 1000 | 1000 |
mongodb_max_connection_size | integer | The maximum size of memory in bytes that may be allocated for
evaluating any query on any given client connection. A value of
0 specifies no limit. | 0 | 0 |
mongodb_max_server_size | integer | The maximum size of memory in bytes that may be allocated for
evaluating all queries on BI Connector. A value of 0 specifies
no limit. | 0 | 0 |
mongodb_max_stage_size | integer | The maximum size of memory in bytes that may be allocated for
evaluating any query in any given query evaluation stage. A value of
0 specifies no limit. | 0 | 0 |
mongodb_max_varchar_length | integer | Specifies the maximum string length returned for columns using
the VARCHAR data type. A value of 0 specifies
no limit. | 0 | 0 |
mongodb_version_compatibility | string | For mixed cluster MongoDB installations, the minimum version of
any process within the cluster. | none | none |
mongodb_git_version | string | The git version of MongoDB the BI Connector is connected to. | none | none |
mongodb_topology | string | The MongoDB cluster topology the BI Connector is connected to. | none | none |
mongodb_version | string | The MongoDB version the BI Connector is connected to. | none | none |
mongosqld_version | string | The BI Connector version. | none | none |
optimize_cross_joins | boolean | If enabled, cross joins are optimized into inner joins when possible. | true | true |
optimize_evaluations | boolean | If enabled, constant-folding is performed. | true | true |
optimize_filtering | boolean | If enabled, predicates in WHERE clauses are moved as close as possible
to the MongoDB data source they operate on. | true | true |
optimize_inner_joins | boolean | If enabled, inner joins are reordered for more optimal query execution. | true | true |
optimize_self_joins | boolean | If enabled, attempt to translate joins between tables with the same
underlying MongoDB collection without $lookup. | true | true |
optimize_view_sampling | boolean | If enabled, the $sample
stage is moved ahead of pipeline stages which do not alter cardinality during
sampling of a MongoDB view. | true | true |
polymorphic_type_conversion_mode | string | Determines how BI Connector evaluates document fields that are
specified with multiple data types. For example, Set
| off | off |
pushdown | boolean | If enabled, queries are translated to MongoDB's native aggregation
language. | true | true |
sample_refresh_interval_secs | integer | Specifies how frequently, in seconds, that the BI Connector schema
is updated. A value of See Cached Sampling for more information. | 0 | 0 |
sample_size | integer | Specifies how many documents BI Connector samples when generating
its schema. A value of See Cached Sampling for more information. | 100 | 100 |
schema_mapping_mode | string | Specifies how the MongoDB schema is transformed into a relational schema:
| lattice | lattice |
type_conversion_mode | string | Specifies the semantics that BI Connector uses for type conversions,
such as the
| mongosql | mongosql |
Setting System Variables
You must have the atlasAdmin database role to set environment
variables on an Atlas-hosted BI Connector. To set them for a self-managed
BI Connector, you must have the inprog privilege on the
MongoDB database to which you've connected the BI Connector.
Use any SQL client that is connected to BI Connector to set these
variables. The following example sets mongodb_max_varchar_length
to 100:
SET GLOBAL mongodb_max_varchar_length = 100
You must start a new connection to the BI Connector after setting a system variable. The connection you used to set the system variable is not affected.