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Spider Server System Variables

The following variables are available when the Spider storage engine has been installed.

See Server System Variables for a complete list of system variables and instructions on setting them.

See also the Full list of MariaDB options, system and status variables.

spider_auto_increment_mode

  • Description: The auto increment mode.
    • -1 Uses the table parameter.
    • 0 Normal Mode. Uses a counter that Spider gets from the remote backend server with an exclusive lock for the auto-increment value. This mode is slow. Use Quick Mode (2), if you use Spider tables with the table partitioning feature and the auto-increment column is the first column of the index.
    • 1 Quick Mode. Uses an internal Spider counter for the auto-increment value. This mode is fast, but it is possible for duplicates to occur when updating the same table from multiple Spider proxies.
    • 2 Set Zero Mode. The auto-increment value is given by the remote backend. Sets the column to 0, even if you set the value to the auto-increment column in your statement. If you use the table with the table partitioning feature, it sets to zero after choosing an inserted partition.
    • 3 When the auto-increment column is set to NULL, the value is given by the remote backend server. If you set the auto-increment column to 0,the value is given by the local server. Set spider_reset_auto_incremnet to 2 or 3 if you want to use an auto-increment column on the remote server.
  • Scope: Global, Session
  • Dynamic: Yes
  • Data Type: numeric
  • Default Session Value: -1
  • Default Table Value: 0
  • Range: -1 to 3
  • DSN Parameter Name: aim

spider_bgs_first_read

  • Description: Number of first read records to use when performing a concurrent background search. To start a range scan on the remote backend, the storage engine first needs to send the first record. Fetching a second record in the same query can save a network round trip stopping the plan if the backend has a single record. The first and second reads are used to warm up for background search. When not using spider_split_read and spider_semi_split_read, the third read fetches the remaining data source in a single fetch.
    • -1 Uses the table parameter.
    • 0 Records are usually retrieved.
    • 1 and greater: Number of records.
  • Scope: Global, Session
  • Dynamic: Yes
  • Data Type: numeric
  • Default Session Value: -1
  • Default Table Value: 2
  • Range: -1 to 9223372036854775807
  • DSN Parameter Name: bfr

spider_bgs_mode

  • Description: Background search mode. This enables the use of a thread per data server connection if the query is not shard-based and must be distributed across shards. The partitioning plugin scans partitions one after the other to optimize memory usage. Because the shards are external, reading all shards can be performed in parallel when the plan prunes multiple partitions.
    • -1 Uses the table parameter.
    • 0 Disables background search.
    • 1 Uses background search when searching without locks
    • 2 Uses background search when searching without locks or with shared locks.
    • 3 Uses background search regardless of locks.
  • Scope: Global, Session
  • Dynamic: Yes
  • Data Type: numeric
  • Default Session Value: -1
  • Default Table Value: 0
  • Range: -1 to 3
  • DSN Parameter Name: bmd

spider_bgs_second_read

  • Description: Number of second read records on the backend server when using background search. When the first records are found from spider_bgs_first_read, the engine continues scanning a range adding a LIMIT of spider_bgs_first_read and spider_bgs_second_read.
    • -1 Uses the table parameter.
    • 0 Records are usually retrieved.
    • 1 and greater: Number of records.
  • Scope: Global, Session
  • Dynamic: Yes
  • Default Session Value: -1
  • Default Table Value: 100
  • Range: -1 to 9223372036854775807
  • DSN Parameter Name: bsr

spider_bka_engine

  • Description: Storage engine used with temporary tables when the spider_bka_mode system variable is set to 1. Defaults to the value of the table parameter, which is MEMORY by default.
  • Scope: Global, Session
  • Dynamic: Yes
  • Data Type: string
  • Default Session Value: ""
  • Default Table Value: Memory
  • DSN Parameter Name: bke

spider_bka_mode

  • Description: Internal action to perform when multi-split reads are disabled. If the spider_multi_split_read system variable is set to 0, Spider uses this variable to determine how to handle statements when the optimizer resolves range retrieval to multiple conditions.
    • -1 Uses the table parameter.
    • 0 Uses "union all".
    • 1 Uses a temporary table, if it is judged acceptable.
    • 2 Uses a temporary table, if it is judged acceptable and avoids replication delay.
  • Scope: Global, Session
  • Dynamic: Yes
  • Data Type: numeric
  • Default Session Value: -1
  • Default Table Value: 1
  • Range: -1 to 2
  • DSN Parameter Name: bkm

spider_bka_table_name_type

  • Description: The type of temporary table name for bka.
  • Scope: Global, Session
  • Dynamic: Yes
  • Data Type: numeric
  • Default Session Value: -1
  • Range: -1 to 1
  • Introduced: MariaDB 10.1.5

spider_block_size

  • Description: Size of memory block used in MariaDB. Can usually be left unchanged.
  • Scope: Global, Session
  • Dynamic: Yes
  • Data Type: numeric
  • Default Session Value: 16384
  • Range: 0 to 4294967295
  • DSN Parameter Name: bsz

spider_bulk_size

  • Description: Size in bytes of the buffer when multiple grouping multiple INSERT statements in a batch, (that is, bulk inserts).
    • -1 The table parameter is adopted.
    • 0 or greater: Size of the buffer.
  • Scope: Global, Session
  • Dynamic: Yes
  • Data Type: numeric
  • Default Session Value: -1
  • Default Table Value: 16000
  • Range: -1 to 2147483647
  • DSN Parameter Name: bsz

spider_bulk_update_mode

  • Description: Bulk update and delete mode. Note: If you use a non-default value for the spider_bgs_mode or spider_split_read system variables, Spider sets this variable to 2.
    • -1 Uses the table parameter.
    • 0 Sends UPDATE and DELETE statements one by one.
    • 1 Collects multiple UPDATE and DELETE statements, then sends the collected statements one by one.
    • 2 Collects multiple UPDATE and DELETE statements and sends them together.
  • Scope: Global, Session
  • Dynamic: Yes
  • Data Type: numeric
  • Default Session Value: -1
  • Default Table Value: 0
  • Range: -1 to 2
  • DSN Parameter Name: bum

spider_bulk_update_size

  • Description: Size in bytes for UPDATE and DELETE queries when generating bulk updates.
    • -1 The table parameter is adopted.
    • 0 or greater: Size of buffer.
  • Scope: Global, Session
  • Dynamic: Yes
  • Data Type: numeric
  • Default Session Value: -1
  • Default Table Value: 16000
  • Range: -1 to 2147483647
  • DSN Parameter Name: bus

spider_casual_read

  • Description: Casual Reads enables all isolation levels, (such as repeatable reads) to work with transactions on multiple backends. With auto-commit queries, you can relax read consistency and run on multiple connections to the backends. This enables parallel queries across partitions, even if multiple shards are stored on the same physical server.
    • -1 Use table parameter.
    • 0 Use casual read.
    • 1 Choose connection channel automatically.
    • 2 to 63 Number of connection channels.
  • Scope: Global, Session
  • Dynamic: Yes
  • Data Type: numeric
  • Default Session Value: -1
  • Default Table Value: 0
  • Range: -1 to 63
  • DSN Parameter Name: ##

spider_conn_recycle_mode

  • Description: Connection recycle mode.
    • 0 Disconnect.
    • 1 Recycle by all sessions.
    • 2 Recycle in the same session.
  • Scope: Global, Session
  • Dynamic: Yes
  • Data Type: numeric
  • Range: 0 to 2
  • Default Session Value: 0

spider_conn_recycle_strict

  • Description: Whether to force the creation of new connections.
    • 1 Don't force.
    • 0 Force new connection
  • Scope: Global, Session
  • Dynamic: Yes
  • Data Type: numeric
  • Default Session Value: 0
  • Range: 0 to 1

spider_conn_wait_timeout

  • Description: Max waiting time in seconds for Spider to get a remote connection.
  • Scope: Global, Session
  • Dynamic: Yes
  • Data Type: numeric
  • Default Session Value: 10
  • Range: 0 to 1000
  • Introduced: MariaDB 10.3.3

spider_connect_error_interval

  • Description: Return same error code until interval passes if connection is failed
  • Scope: Global,
  • Dynamic: Yes
  • Data Type: numeric
  • Default Value: 1
  • Introduced: MariaDB 10.0.23

spider_connect_mutex

  • Description: Whether to serialize remote servers connections (use mutex at connecting). Use this parameter if you get an error or slowdown due to too many connection processes.
    • 0 Not serialized.
    • 1 : Serialized.
  • Scope: Global, Session
  • Dynamic: Yes
  • Data Type: boolean
  • Default Session Value: 0

spider_connect_retry_count

  • Description: Number of times to retry connections that fail due to too many connection processes.
  • Scope: Global, Session
  • Dynamic: Yes
  • Data Type: numeric
  • Default Session Value: 1000
  • Range: 0 to 2147483647

spider_connect_retry_interval

  • Description: Interval in microseconds for connection failure due to too many connection processes.
  • Scope: Global, Session
  • Dynamic: Yes
  • Data Type: numeric
  • Default Session Value: 1000
  • Range: -1 to 9223372036854775807#

spider_connect_timeout

  • Description: Timeout in seconds to declare remote backend unresponsive when opening a connection. Change for high-latency networks.
    • -1 The table parameter is adopted.
    • 0 Less than 1.
    • 1 and greater: Number of seconds.
  • Scope: Global, Session
  • Dynamic: Yes
  • Data Type: numeric
  • Default Session Value: -1
  • Default Table Value: 0
  • Range: -1 to 2147483647
  • DSN Parameter Name: cto

spider_crd_bg_mode

  • Description: Indexes cardinality statistics in the background. Disable when the spider_crd_mode system variable is set to 3 or when the spider_crd_interval variable is set to 0.
    • -1 Uses the table parameter.
    • 0 Disables background confirmation.
    • 2 Enables background confirmation.
  • Scope: Global, Session
  • Dynamic: Yes
  • Data Type: numeric
  • Default Session Value: -1
  • Default Table Value: 1
  • Range: -1 to 1
  • DSN Parameter Name: cbm

spider_crd_interval

  • Description: Time interval in seconds of index cardinality statistics. Set to 0 to always get the latest information from remote servers.
    • -1 The table parameter is adopted.
    • 1 or more: Interval in seconds table state confirmation.
  • Scope: Global, Session
  • Dynamic: Yes
  • Data Type: numeric
  • Default Session Value: -1
  • Default Table Value: 51
  • Range: -1 to 2147483647
  • DSN Parameter Name: civ

spider_crd_mode

  • Description: Mode for index cardinality statistics. By default, uses SHOW at the table-level.
    • -1,0 Uses the table parameter.
    • 1 Uses the SHOW command.
    • 2 Uses the Information Schema.
    • 3 Uses the EXPLAIN command.
  • Scope: Global, Session
  • Dynamic: Yes
  • Data Type: numeric
  • Default Session Value: -1
  • Default Table Value: 1
  • Range: -1 to 3
  • DSN Parameter Name: cmd

spider_crd_sync

  • Description: Synchronize index cardinality statistics in partitioned tables.
    • -1 Uses the table parameter.
    • 0 Disables synchronization.
    • 1 Uses table state synchronization when opening a table, but afterwards performs no synchronization.
    • 2 Enables synchronization.
  • Scope: Global, Session
  • Dynamic: Yes
  • Data Type: numeric
  • Default Session Value: -1
  • Default Table Value: 0
  • Range: -1 to 2
  • DSN Parameter Name: csy

spider_crd_type

  • Description: Type of cardinality calculation. Only effective when the spider_crd_mode system variable is set to use SHOW (1) or to use the Information Schema (2).
    • -1 Uses the table parameter.
    • 0 Uses the value of the spider_crd_weight system variable, as a fixed value.
    • 1 Uses the value of the spider_crd_weight system variable, as an addition value.
    • 2 Uses the value of the spider_crd_weight system variable, as a multiplication value.
  • Scope: Global, Session
  • Dynamic: Yes
  • Data Type: numeric
  • Default Session Value: -1
  • Default Table Value: 2
  • Range: -1 to 2
  • DSN Parameter Name: ctp

spider_crd_weight

  • Description: Weight coefficient used to calculate effectiveness of index from the cardinality of column. For more information, see the description for the spider_crd_type system variable.
    • -1 Uses the table parameter.
    • 0 or greater: Weight.
  • Scope: Global, Session
  • Dynamic: Yes
  • Data Type: numeric
  • Default Session Value: -1
  • Default Table Value: 2
  • Range: -1 to 2147483647
  • DSN Parameter Name: cwg

spider_delete_all_rows_type

  • Description: The type of delete_all_rows.
  • Scope: Global, Session
  • Dynamic: Yes
  • Data Type: numeric
  • Default Session Value: -1
  • Range: -1 to 1
  • Introduced: Spider 3.2

spider_direct_dup_insert

  • Description: Manages duplicate key check for REPLACE, INSERT IGNORE and LOAD DATA LOCAL INFILE to remote servers. This can save on network roundtrips if the key always maps to a single partition. For bulk operations, records are checked for duplicate key errors one by one on the remote server, unless you set it to avoid duplicate checks on local servers (1).
    • -1 Uses the table parameter.
    • 0 Performs duplicate checks on the local server.
    • 1 Avoids duplicate checks on the local server.
  • Scope: Global, Session
  • Dynamic: Yes
  • Data Type: numeric
  • Default Session Value: -1
  • Default Table Value: 0
  • Range: -1 to 1
  • DSN Parameter Name: ddi

spider_direct_order_limit

  • Description: Pushes ORDER BY and LIMIT operations to the remote server.
    • -1 Uses the table parameter.
    • 0 Uses local execution.
    • 1 Uses push down execution.
  • Scope: Global, Session
  • Dynamic: Yes
  • Data Type: numeric
  • Default Session Value: -1
  • Default Table Value: 0
  • Range: -1 to 9223372036854775807
  • DSN Parameter Name: dol

spider_dry_access

  • Description: Simulates an empty result-set. No queries are sent to the backend. Use for performance tuning.
    • 0 Normal access.
    • 1 All access from Spider to data node is suppressed.
  • Scope: Global
  • Dynamic: No
  • Data Type: boolean
  • Default Value: OFF

spider_error_read_mode

  • Description: Sends an empty result-set when reading a backend server raises an error. Useful with applications that don't implement transaction replays.
    • -1 Uses the table parameter.
    • 0 Returns an error.
    • 1 Returns an empty result.
  • Scope: Global, Session
  • Dynamic: Yes
  • Data Type: numeric
  • Default Session Value: -1
  • Default Table Value: 0
  • Range: -1 to 1
  • DSN Parameter Name: erm

spider_error_write_mode

  • Description: Sends an empty result-set when writing to a backend server raises an error. Useful with applications that don't implement transaction replays.
    • -1 Uses the table parameter.
    • 0 Returns an error.
    • 1 Returns an empty result-set on error.
  • Scope: Global, Session
  • Dynamic: Yes
  • Data Type: numeric
  • Default Session Value: -1
  • Default Table Value: 0
  • Range: -1 to 1
  • DSN Parameter Name: ewm

spider_first_read

  • Description: Number of first read records to start a range scan on the backend server. Spider needs to send the first record. Fetching the second record saves network round-trips, stopping the plan if the backend has a single record. First read and second read are used to warm up for background searches, third reads without using the spider_split_read and spider_semi_split_read system variables fetches the remaining data source in a single last fetch.
    • -1 Use the table parameter.
    • 0 Usually retrieves records.
    • 1 and greater: Sets the number of first read records.
  • Scope: Global, Session
  • Dynamic: Yes
  • Data Type: numeric
  • Default Session Value: -1
  • Default Table Value: 2
  • Range: -1 to 9223372036854775807
  • DSN Parameter Name: frd

spider_force_commit

  • Description: Behavior when error occurs on XA PREPARE, XA COMMIT, and XA ROLLBACK statements.
    • 0 Returns the error.
    • 1 Returns the error when the xid doesn't exist, otherwise it continues processing the XA transaction.
    • 2 Continues processing the XA transaction, disregarding all errors.
  • Scope: Global, Session
  • Dynamic: Yes
  • Data Type: numeric
  • Default Session Value: 0
  • Range: 0 to 2

spider_general_log

  • Description: Whether Spider logs all commands to the General Log. Spider logs error codes according to the spider_log_result_errors system variable.
    • OFF Logs no commands.
    • ON Logs commands to the General Log.
  • Scope: Global, Session
  • Dynamic: Yes
  • Data Type: boolean
  • Default Session Value: OFF

spider_index_hint_pushdown

  • Description: Whether to use Push Down index hints, like force_index.
  • Scope: Global, Session
  • Dynamic: Yes
  • Data Type: boolean
  • Default Session Value: OFF
  • Introduced: MariaDB 10.3.3

spider_init_sql_alloc_size

  • Description: Initial size of the local SQL buffer.
    • -1 Uses the table parameter.
    • 0 or greater: Size of the buffer.
  • Scope: Global, Session
  • Dynamic: Yes
  • Data Type: numeric
  • Default Session Value: -1
  • Default Table Value: 1024
  • DSN Parameter Name: isa
  • Range: -1 to 2147483647

spider_internal_limit

  • Description: Limits the number of records when acquired from a remote server.
    • -1 The table parameter is adopted.
    • 0 or greater: Records limit.
  • Scope: Global, Session
  • Dynamic: Yes
  • Data Type: numeric
  • Default Session Value: -1
  • Default Table Value: 9223372036854775807
  • Range: -1 to 9223372036854775807
  • DSN Parameter Name: ilm

spider_internal_offset

  • Description: Skip records when acquired from the remote server.
    • -1 Uses the table parameter.
    • 0 or more : Number of records to skip.
  • Scope: Global, Session
  • Dynamic: Yes
  • Data Type: numeric
  • Default Session Value: -1
  • Default Table Value: 0
  • Range: -1 to 9223372036854775807
  • DSN Parameter Name: ios

spider_internal_optimize

  • Description: Whether to perform push down operations for OPTIMIZE TABLE statements.
    • -1 Uses the table parameter.
    • 0 Transmitted.
    • 1 Not transmitted.
  • Scope: Global, Session
  • Dynamic: Yes
  • Data Type: numeric
  • Default Session Value: -1
  • Default Table Value: 0
  • Range: -1 to 1
  • DSN Parameter Name: iom

spider_internal_optimize_local

  • Description: Whether to transmit to remote servers when OPTIMIZE TABLE statements are executed on the local server.
    • -1 Uses the table parameter.
    • 0 Not transmitted.
    • 1 Transmitted.
  • Default Session Value: -1
  • Range: -1 to 1
  • DSN Parameter Name: iol

spider_internal_sql_log_off

  • Description: Whether to log SQL statements sent to the remote server in the General Query Log. Explicitly setting this system variable to either ON or OFF causes the Spider node to send a SET sql_log_off statement to each of the data nodes using the SUPER privilege.
    • OFF Logs SQL statements to the remote server.
    • ON Doesn't log SQL statements to the remote server.
  • Scope: Global, Session
  • Dynamic: Yes
  • Data Type: boolean
  • Default Session Value: ON

spider_internal_unlock

  • Description: Whether to transmit unlock tables to the connection of the table used with SELECT statements.
    • 0 Not transmitted.
    • 1 Transmitted.
  • Data Type: boolean
  • Default Session Value: 0

spider_internal_xa

  • Description: Whether to implement XA at the server- or storage engine-level. When using the server-level, set different values for the server_id system variable on all server instances to generate different xid values.
    • OFF Uses the storage engine protocol.
    • ON Uses the server protocol.
  • Scope: Global, Session
  • Dynamic: Yes
  • Data Type: boolean
  • Default Session Value: OFF

spider_internal_xa_id_type

  • Description: The type of internal_xa id.
  • Scope: Global, Session
  • Dynamic: Yes
  • Data Type: numeric
  • Default Session Value: 0
  • Range: -1 to 1

spider_internal_xa_snapshot

  • Description: Limitation for reading consistent data on all backend servers when using MariaDB's internal XA implementation and START TRANSACTION WITH CONSISTENT SNAPSHOT.
    • 0 Raise error when using a Spider table.
    • 1 Raise error when issued a START TRANSACTION statement.
    • 2 Takes a consistent snapshot on each backend, but loses global consistency.
    • 3 Starts transactions with XA, but removes CONSISTENT SNAPSHOT.
  • Scope: Global, Session
  • Dynamic: Yes
  • Data Type: numeric
  • Range: 0 to 3
  • Default Session Value: 0

spider_load_crd_at_startup

  • Description: Loads CRD from the system table at startup.
  • Scope: Global, Session
  • Dynamic: Yes
  • Data Type: boolean
  • Default Session Value: -1
  • Introduced: MariaDB 10.3.3

spider_load_sts_at_startup

  • Description: Loads STS from the system table at startup.
  • Scope: Global, Session
  • Dynamic: Yes
  • Data Type: boolean
  • Default Session Value: -1
  • Introduced: MariaDB 10.3.3

spider_local_lock_table

  • Description: Whether to push LOCK TABLES statements down to the remote server.
    • 0 Transmitted.
    • 1 Not transmitted.
  • Scope: Global, Session
  • Dynamic: Yes
  • Data Type: boolean
  • Default Session Value: 0

spider_lock_exchange

spider_log_result_error_with_sql

  • Description: Logs SQL statements with result errors.
  • Dynamic: Yes
  • Data Type: numeric
  • Default Session Value: 0
  • Range: 0 to 3

spider_log_result_errors

  • Description: Log results from data nodes to the Spider node in the Error Log. Performs no logging by default.
    • 0 : Logs no errors from data nodes.
    • 1 : Logs errors from data nodes.
    • 2 : Logs errors from data nodes, as well as warning summaries.
    • 3 : Logs errors from data nodes, as well as warning summaries and details.
    • 4 : Logs errors from data nodes, as well as warning summaries and details, and result summaries.
  • Dynamic: Yes
  • Data Type: numeric
  • Default Session Value: 0
  • Range: 0 to 4

spider_low_mem_read

  • Description: Whether to use low memory mode when executing queries issued internally to remote servers that return result-sets.
    • -1 Uses the table parameter.
    • 0 Doesn't use low memory mode.
    • 1 Uses low memory mode.
  • Data Type: numeric
  • Default Value: -1
  • Range: -1 to 1

spider_max_connections

  • Description: Maximum number of connections from Spider to a remote MariaDB servers. Defaults to 0, which is no limit.
  • Command-line: --spider-max-connections
  • Scope: Global, Session
  • Dynamic: Yes
  • Data Type: numeric
  • Default Session Value: 0
  • Range: 0 to 99999
  • Introduced: MariaDB 10.3.3

spider_max_order

  • Description: Maximum number of columns for ORDER BY operations.
    • -1 The table parameter is adopted.
    • 0 and greater: Maximum number of columns.
  • Scope: Global, Session
  • Dynamic: Yes
  • Data Type: numeric
  • Default Session Value: -1
  • Default Table Value: 32767#
  • Range: -1 to 32767
  • DSN Parameter Name: mod

spider_multi_split_read

  • Description: Whether to divide a statement into multiple SQL statements sent to the remote backend server when the optimizer resolves range retrievals to multiple conditions.
    • -1 Uses the table parameter.
    • 0 Doesn't divide statements.
    • 1 Divides statements.
  • Scope: Global, Session
  • Dynamic: Yes
  • Data Type: numeric
  • Default Session Value: -1
  • Default Table Value: 0
  • Range: -1 to 2147483647
  • DSN Parameter Name: msr

spider_net_read_timeout

  • Description: TCP timeout in seconds to declare remote backend servers unresponsive when reading from a connection. Change for high latency networks.
    • -1 Uses the table parameter.
    • 0 Less than 1 second timeout.
    • 1 and greater: Timeout in seconds.
  • Scope: Global, Session
  • Dynamic: Yes
  • Data Type: numeric
  • Default Session Value: -1
  • Default Table Value: 0
  • Range: -1 to 2147483647
  • DSN Parameter Name: nrt

spider_net_write_timeout

  • Description: TCP timeout in seconds to declare remote backend servers unresponsive when writing to a connection. Change for high latency networks.
    • -1 The table parameter is adopted.
    • 0 Less than 1 second timeout.
    • 1 and more: Timeout in seconds.
  • Scope: Global, Session
  • Dynamic: Yes
  • Data Type: numeric
  • Default Session Value: -1
  • Default Table Value: 0
  • Range: -1 to 2147483647
  • DSN Parameter Name: nwt

spider_ping_interval_at_trx_start

  • Description: Resets the connection with keepalive timeout in seconds by sending a ping.
    • 0 At every transaction.
    • 1 and greater: Number of seconds.
  • Scope: Global, Session
  • Dynamic: Yes
  • Data Type: numeric
  • Max Value: 2147483647
  • Default Session Value: 3600
  • Range: 0 to 2147483647

spider_quick_mode

  • Description: Sets the backend query buffering to cache on the remote backend server or in the local buffer.
    • -1 Uses the table parameter.
    • 0 Local buffering, it acquires records collectively with store_result.
    • 1 Remote buffering, it acquires records one by one. Interrupts don't wait and recovery on context switch back.
    • 2 Remote buffering, it acquires records one by one. Interrupts wait to the end of the acquisition.
    • 3 Local buffering, uses a temporary table on disk when the result-set is greater than the value of the spider_quick_page_size system variable.
  • Scope: Global, Session
  • Dynamic: Yes
  • Data Type: numeric
  • Default Session Value: -1
  • Default Table Value: 0
  • Range: -1 to 3
  • DSN Parameter Name: qmd

spider_quick_page_size

  • Description: Number of records in a page when acquired record by record.
    • -1 The table parameter is adopted.
    • 0 or greater: Number of records.
  • Scope: Global, Session
  • Dynamic: Yes
  • Data Type: numeric
  • Default Session Value: -1
  • Default Table Value: 100
  • Range: -1 to 9223372036854775807
  • DSN Parameter Name: qps

spider_read_only_mode

  • Description: Whether to allow writes on Spider tables.
    • -1 Uses the table parameter.
    • 0 Allows writes to Spider tables.
    • 1 Makes tables read- only.
  • Scope: Global, Session
  • Dynamic: Yes
  • Data Type: numeric
  • Default Session Value: -1
  • Default Table Value: 0
  • Range: -1 to 1
  • DSN Parameter Name: rom

spider_remote_access_charset

  • Description: Forces session character set when connecting to the backend server. This can improve connection time performance.
  • Scope: Global, Session
  • Dynamic: Yes
  • Data Type: string
  • Default Session Value: null

spider_remote_autocommit

  • Description: Sets the auto-commit mode when connecting to backend servers. This can improve connection time performance.
    • -1 Doesn't change the auto-commit mode.
    • 0 Sets the auto-commit mode to 0.
    • 1 Sets the auto-commit mode to 1.
  • Scope: Global, Session
  • Dynamic: Yes
  • Data Type: numeric
  • Default Session Value: -1
  • Range: -1 to 1

spider_remote_default_database

  • Description: Sets the local default database when connecting to backend servers. This can improve connection time performance.
    • 0 OFF
    • 1 ON
  • Scope: Global, Session
  • Dynamic: Yes
  • Data Type: string
  • Default Session Value: Empty string

spider_remote_sql_log_off

  • Description: Sets the sql_log_off system variable to use when connecting to backend servers.
    • -1 Doesn't set the value.
    • 0 Doesn't log Spider SQL statements to remote backend servers.
    • 1 Logs SQL statements on remote backend
  • Scope: Global, Session
  • Dynamic: Yes
  • Data Type: numeric
  • Default Session Value: -1
  • Range: -1 to 1

spider_remote_time_zone

  • Description: Forces the time zone setting when connecting to backend servers. This can improve connection performance when you know the time zone.
  • Scope: Global, Session
  • Dynamic: Yes
  • Data Type: string
  • Default Session Value: null

spider_remote_trx_isolation

  • Description: Sets the Transaction Isolation Level when connecting to the backend server.
    • -1 Doesn't set the Isolation Level.
    • 0 Sets to the READ UNCOMMITTED level.
    • 1 Sets to the READ COMMITTED level.
    • 2 Sets to the REPEATABLE READ level.
    • 3 Sets to the SERIALIZABLE level.
  • Scope: Global, Session
  • Dynamic: Yes
  • Data Type: numeric
  • Default Session Value: -1
  • Range: -1 to 3

spider_reset_sql_alloc

  • Description: Resets the per connection SQL buffer after an SQL statement executes.
    • -1 Uses the table parameter.
    • 0 Doesn't reset.
    • 1 Resets.
  • Scope: Global, Session
  • Dynamic: Yes
  • Data Type: numeric
  • Default Session Value: -1
  • Default Table Value: 1
  • Range: -1 to 1
  • DSN Parameter Name: rsa
  • Description: Enables the linking of a table to the same local instance.
    • 0 Disables linking.
    • 1 Enables linking.
  • Scope: Global, Session
  • Dynamic: Yes
  • Data Type: boolean
  • Default Session Value: OFF

spider_second_read

  • Description: Number of second read records on the backend server when the first records are found from the first read. Spider continues scanning a range, adding a LIMIT using the spider_first_read and spider_second_read variables.
    • -1 Uses the table parameter.
    • 0 Usually retrieves records.
    • 1 and greater: Number of records.
  • Scope: Global, Session
  • Dynamic: Yes
  • Default Session Value: -1
  • Default Table Value: 9223372036854775807
  • Range: -1 to 9223372036854775807
  • DSN Parameter Name: srd

spider_select_column_mode

  • Description: Mode for column retrieval from remote backend server.
    • -1 Uses the table parameter.
    • 0 Uses index columns when the SELECT statement can resolve with an index, otherwise uses all columns.
    • 1 Uses all columns judged necessary to resolve the query.
  • Scope: Global, Session
  • Dynamic: Yes
  • Data Type: numeric
  • Default Session Value: -1
  • Default Table Value: 1
  • Range: -1 to 1
  • DSN Parameter Name: scm

spider_selupd_lock_mode

  • Description: Local lock mode on INSERT SELECT.
    • -1 Uses the table parameter.
    • 0 Takes no locks.
    • 1 Takes shared locks.
    • 2 Takes exclusive locks.
  • Scope: Global, Session
  • Dynamic: Yes
  • Data Type: numeric
  • Default Session Value: -1
  • Default Table Value: 1
  • Range: -1 to 2
  • DSN Parameter Name: slm#

spider_semi_split_read

  • Description: Whether to use chunk retrieval with offset and limit parameters on SQL statements sent to the remote backend server when using the spider_split_read system variable.
    • -1 Uses the table parameter.
    • 0 Doesn't use chunk retrieval.
    • 1 or more Uses chunk retrieval.
  • Scope: Global, Session
  • Dynamic: Yes
  • Data Type: numeric
  • Default Session Value: -1
  • Default Table Value: 0
  • Range: -1 to 2147483647
  • DSN Parameter Name: ssr#

spider_semi_split_read_limit

  • Description: Sets the limit value for the spider_semi_split_read system variable.
    • -1 Uses the table parameter.
    • 0 or more: The limit value.
  • Scope: Global, Session
  • Dynamic: Yes
  • Data Type: numeric
  • Default Session Value: -1
  • Default Table Value: 9223372036854775807
  • Range: -1 to 9223372036854775807
  • DSN Parameter Name: ssl#

spider_semi_table_lock

  • Description: Enables semi-table locking. This adds a LOCK TABLES statement to SQL executions sent to the remote backend server when using non-transactional storage engines to preserve consistency between roundtrips.
    • 0 Disables semi-table locking.
    • 1 Enables semi-table locking.
  • Scope: Global, Session
  • Dynamic: Yes
  • Data Type: numeric
  • Default Session Value: 1
  • Range: 0 to 1
  • DSN Parameter Name: stl#

spider_semi_table_lock_connection

  • Description: Whether to use multiple connections with semi-table locking. To enable semi-table locking, use the spider_semi_table_lock system variable.
    • -1 Uses the table parameter.
    • 0 Uses the same connection.
    • 1 Uses different connections.
  • Scope: Global, Session
  • Dynamic: Yes
  • Data Type: numeric
  • Default Session Value: -1
  • Default Table Value: 1
  • Range: -1 to 1
  • DSN Parameter Name: stc#

spider_semi_trx

  • Description: Enables semi-transactions. This controls transaction consistency when an SQL statement is split into multiple statements issued to the backend servers. You can preserve or relax consistency as need. Spider encapsulates auto-committed SQL statements within a transaction on the remote backend server. When using READ COMMITTED or READ UNCOMMITTED transaction isolation levels to force consistency, set the spider_semi_trx_isolation system variable to 2.
    • 0 Disables semi-transaction consistency.
    • 1 Enables semi-transaction consistency.
  • Scope: Global, Session
  • Dynamic: Yes
  • Data Type: boolean
  • Default Session Value: ON

spider_semi_trx_isolation

  • Description: Set consistency during range SQL execution when spider_sync_trx_isolation is 1
    • -1 OFF
    • 0 READ UNCOMMITTED
    • 1 READ COMMITTED
    • 2 REPEATABLE READ
    • 3 SERIALIZABLE
  • Scope: Global, Session
  • Dynamic: Yes
  • Data Type: numeric
  • Default Session Value: -1
  • Range: -1 to 3

spider_skip_default_condition

  • Description: Whether to compute condition push downs.
    • -1 Uses the table parameter.
    • 0 Computes condition push downs.
    • 1 Doesn't compute condition push downs.
  • Scope: Global, Session
  • Dynamic: Yes
  • Data Type: numeric
  • Default Session Value: -1
  • Default Table Value: 0
  • Range: -1 to 1
  • DSN Parameter Name: sdc
  • Description: Whether to skip parallel search by specific conditions.
  • Commandline: --spider-skip-parallel-search=#
  • Scope: Session
  • Dynamic: Yes
  • Data Type: numeric
  • Default Session Value: -1
  • Range: -1 to 3
  • Introduced: MariaDB 10.3.3

spider_split_read

  • Description: Number of records in chunk to retry the result when a range query is sent to remote backend servers.
    • -1 Uses the table parameter.
    • 0 or more: Number of records.
  • Scope: Global, Session
  • Dynamic: Yes
  • Data Type: numeric
  • Default Session Value: -1
  • Default Table Value: 9223372036854775807
  • Range: -1 to 9223372036854775807
  • DSN Parameter Name: srd

spider_store_last_crd

  • Description: Stores last CRD result in the system table.
  • Commandline: --spider-store-last-crd=#
  • Scope: Global
  • Dynamic: Yes
  • Data Type: numeric
  • Default Session Value: -1
  • Range: -1 to 1
  • Introduced: MariaDB 10.3.3

spider_store_last_sts

  • Description: Stores last STS result into system table.
  • Commandline: --spider-store-last-sts=#
  • Scope: Global
  • Dynamic: Yes
  • Data Type: numeric
  • Default Session Value: -1
  • Range: -1 to 1
  • Introduced: MariaDB 10.3.3

spider_sts_bg_mode

  • Description: Enables background confirmation for table statistics. When background confirmation is enabled, Spider uses one thread per partition to maintain table status. Disable when the spider_sts_interval system variable is set to 0, which causes Spider to always retrieve the latest information as need. It is effective, when the spider_sts_interval system variable is set to 10.
    • -1 Uses the table parameter.
    • 0 Disables background confirmation.
    • 1 Enables background confirmation.
  • Scope: Global, Session
  • Dynamic: Yes
  • Data Type: numeric
  • Default Session Value: -1
  • Default Table Value: 1
  • Range: -1 to 1
  • DSN Parameter Name: sbm

spider_sts_interval

  • Description: Time interval of table statistics from the remote backend servers.
    • -1 Uses the table parameter.
    • 0 Retrieves the latest table statistics on request.
    • 1 or more: Interval in seconds for table state confirmation.
  • Scope: Global, Session
  • Dynamic: Yes
  • Data Type: numeric
  • Default Session Value: -1
  • Default Table Value: 10
  • Range: -1 to 2147483647
  • DSN Parameter Name: siv

spider_sts_mode

  • Description: Table statistics mode. Mode for table statistics. The SHOW command is used at the table level default.
    • -1,0 Uses the table parameter.
    • 1 Uses the SHOW command.
    • 2 Uses the Information Schema.
  • Scope: Global, Session
  • Dynamic: Yes
  • Data Type: numeric
  • Default Session Value: -1
  • Default Table Value: 1
  • Range: -1 to 2
  • DSN Parameter Name: smd

spider_sts_sync

  • Description: Synchronizes table statistics in partitioned tables.
    • -1 Uses the table parameter.
    • 0 Doesn't synchronize table statistics in partitioned tables.
    • 1 Synchronizes table state when opening a table, doesn't synchronize after opening.
    • 2 Synchronizes table statistics.
  • Scope: Global, Session
  • Dynamic: Yes
  • Data Type: numeric
  • Default Session Value: -1
  • Default Table Value: 0
  • Range: -1 to 2
  • DSN Parameter Name: ssy

spider_support_xa

  • Description: XA Protocol for mirroring and for multi-shard transactions.
    • 1 Enables XA Protocol for these Spider operations.
    • 0 Disables XA Protocol for these Spider operations.
  • Scope: Global
  • Dynamic: No
  • Data Type: boolean
  • Default Table Value: 1

spider_sync_autocommit

  • Description: Whether to push down local auto-commits to remote backend servers.
    • OFF Pushes down local auto-commits.
    • ON Doesn't push down local auto-commits.
  • Scope: Global
  • Dynamic: Yes
  • Data Type: boolean
  • Default Session Value: ON

spider_sync_time_zone

  • Description: Whether to push the local time zone down to remote backend servers.
    • OFF Doesn't synchronize time zones.
    • ON Synchronize time zones.
  • Scope: Global
  • Dynamic: Yes
  • Data Type: boolean
  • Default Session Value: OFF
  • Removed: MariaDB 10.3.9

spider_sync_trx_isolation

  • Description: Pushes local transaction isolation levels down to remote backend servers.
    • ON Doesn't push down local isolation levels.
    • OFF Pushes down local isolation levels.
  • Scope: Global
  • Dynamic: Yes
  • Data Type: boolean
  • Default Session Value: ON

spider_table_crd_thread_count

  • Description: Static thread count of table crd.
  • Commandline: --spider-table-crd-thread-count=#
  • Scope: Global
  • Dynamic: No
  • Data Type: numeric
  • Default Value: 10
  • Range: 1 to 4294967295
  • Introduced: MariaDB 10.3.3

spider_table_init_error_interval

  • Description: Interval in seconds where the same error code is returned if table initialization fails. Use to protect against infinite loops in table links.
  • Scope: Global
  • Dynamic: Yes
  • Data Type: numeric
  • Default Value: 1
  • Range: 0 to 4294967295

spider_table_sts_thread_count

  • Description: Static thread count of table sts.
  • Commandline: --spider-table-sts-thread-count=#
  • Scope: Global
  • Dynamic: No
  • Data Type: numeric
  • Default Value: 10
  • Range: 1 to 4294967295
  • Introduced: MariaDB 10.3.3

spider_udf_ct_bulk_insert_interval

  • Description: Interval in milliseconds between bulk inserts at copying.
    • -1 Uses the UDF parameter.
    • 0 and more: Time in milliseconds.
  • Scope: Global
  • Dynamic: Yes
  • Data Type: numeric
  • Default Session Value: -1
  • Default Table Value: 2147483647
  • Range: -1 to 2147483647

spider_udf_ct_bulk_insert_rows

  • Description: Number of rows to insert at a time when copying during bulk inserts.
    • -1, 0: Uses the table parameter.
    • 1 and more: Number of rows
  • Scope: Global
  • Dynamic: Yes
  • Data Type: numeric
  • Default Session Value: -1
  • Default Table Value: 18446744073709551615
  • Range: -1# to 9223372036854775807

spider_udf_ds_bulk_insert_rows

  • Description: Number of rows inserted at a time during bulk inserts when the result-set is stored in a temporary table on executing a UDF.
    • -1, 0 Uses the UDF parameter.
    • 1 or more: Number of rows
  • Scope: Global
  • Dynamic: Yes
  • Data Type: numeric
  • Default Session Value: -1
  • Default Table Value: 9223372036854775807
  • Range: -1# to 9223372036854775807

spider_udf_ds_table_loop_mode

  • Description: Whether to store the result-set in the same temporary table when the temporary table list count for UDF is less than the result-set count on UDF execution.
    • -1 Uses the table parameter.
    • 0 Drops records.
    • 1 Inserts the last table.
    • 2 Inserts hte first table and loops again.
  • Scope: Global, Session
  • Dynamic: Yes
  • Data Type: numeric
  • Default Session Value: -1
  • Range: -1# to 2

spider_udf_ds_use_real_table

  • Description: Use real table for temporary table list.
  • Scope: Global, Session
  • Dynamic: Yes
  • Data Type: numeric
  • Default Session Value: -1
  • Range: -1# to 1

spider_udf_table_lock_mutex_count

  • Description: Mutex count of table lock for Spider UDFs.
  • Scope: Global
  • Dynamic: No
  • Data Type: numeric
  • Default Value: 20
  • Range: 1# to 4294967295

spider_udf_table_mon_mutex_count

  • Description: Mutex count of table mon for Spider UDFs.
  • Scope: Global
  • Dynamic: No
  • Data Type: numeric
  • Default Value: 20
  • Range: 1# to 4294967295

spider_use_all_conns_snapshot

  • Description: Whether to pass START TRANSACTION WITH SNAPSHOT statements to all connections.
    • OFF Doesn't pass statement to all connections.
    • ON Passes statement to all connections.
  • Scope: Global, Session
  • Dynamic: Yes
  • Data Type: boolean
  • Default Session Value: OFF

spider_use_consistent_snapshot

  • Description: Whether to push a local START TRANSACTION WITH CONSISTENT statement down to remote backend servers.
    • OFF Doesn't push the local statement down.
    • ON Pushes the local statement down.
  • Scope: Global, Session
  • Dynamic: Yes
  • Data Type: boolean
  • Default Session Value: OFF

spider_use_default_database

  • Description: Whether to use the default database.
    • OFF Doesn't use the default database.
    • ON Uses the default database.
  • Scope: Global, Session
  • Dynamic: Yes
  • Data Type: boolean
  • Default Session Value: ON

spider_use_flash_logs

  • Description: Whether to push FLUSH LOGS statements down to remote backend servers.
    • OFF Doesn't push the statement down.
    • ON Pushes the statement down.
  • Scope: Global, Session
  • Dynamic: Yes
  • Data Type: boolean
  • Default Session Value: OFF

spider_use_handler

  • Description: Converts HANDLER SQL statements.

When the spider_sync_trx_isolation system variable is set to 0, Spider disables HANDLER conversions to prevent use of the statement on the SERIALIZABLE isolation level. 0 Converts HANDLER statements into SELECT statements. 1 Passes HANDLER to the remote backend server. 2 Converts SQL statements to HANDLER statements. 3 Converts SQL statements to HANDLER statements and HANDLER statements to SQL statements.

  • Scope: Global, Session
  • Dynamic: Yes
  • Data Type: numeric
  • Default Session Value: -1
  • Range: -1# to 3
  • DSN Parameter Name: uhd

spider_use_pushdown_udf

  • Description: When using a UDF function in a condition and the engine_condition_pushdown system variable is set to 1, whether to execute the UDF function locally or push it down.
    • -1 Uses the table parameter.
    • 0 Doesn't transmit the UDF
    • 1 Transmits the UDF.
  • Scope: Global, Session
  • Dynamic: Yes
  • Data Type: numeric
  • Default Session Value: -1
  • Default Table Value: 1
  • Range: -1# to 1
  • DSN Parameter Name: upu

spider_use_snapshot_with_flush_tables

  • Description: Whether to encapsulate FLUSH LOGS and UNLOCK TABLES statements when START TRANSACTION WITH CONSISTENT and FLUSH TABLE WITH READ LOCK statements are sent to the remote backend servers.
  • Scope: Global, Session
  • Dynamic: Yes
  • Data Type: numeric
  • Default Session Value: 0
  • Range: 0# to 2

spider_use_table_charset

  • Description: Whether to use the local table character set for the remote backend server connections.
    • -1 Uses the table parameter.
    • 0 Use utf8.
    • 1 Uses the table character set.
  • Scope: Global, Session
  • Dynamic: Yes
  • Data Type: numeric
  • Default Session Value: -1
  • Default Table Value: 1
  • Range: -1# to 1
  • DSN Parameter Name: utc

spider_version

  • Description: The current Spider version.
  • Scope: Global
  • Dynamic: No
  • Data Type: string

spider_xa_register_mode

  • Description: Mode of XA transaction register into system table.
  • Command-line: --spider-xa-register-mode=#
  • Scope: Global, Session
  • Dynamic: Yes
  • Data Type: numeric
  • Default Value: 1
  • Range: 0 to 1
  • Introduced: MariaDB 10.3.3
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https://mariadb.com/kb/en/spider-server-system-variables/