Spider FAQ

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[ERROR] mysqld: Can't find record in 'spider_tables', what does it mean?

This happen when you have a spider table defined that is not pointing to an existing table on a data node.

Is there some minimum spider setting ?

myisam-recover=FORCE,BACKUP
MariaDB until 10.1.1
optimizer_switch='engine_condition_pushdown=on'
MariaDB until 10.0.12

When using join_cache_level = 6 to get faster joins on the network it is recommended to use :

optimizer_switch='mrr=on,mrr_sort_keys=off' 

see : https://mariadb.atlassian.net/browse/MDEV-5976

What does select spider_ping_table() in the general log means?

This is used by spider monitoring to ask other monitoring nodes the status of a table.

Do i need a primary key on physical tables?

Not having primary key will generate error for resynchronizing tables via spider_copy_table().

Can i use spider on top of Galera shards?

Yes XA transactions can be disable from spider, until Galera 4.0 fully support xa transactions , spider can point to maxscale proxy that can manage transparent node election in case of failure inside a shard group. Note that disabling XA will break cross shard WRITES in case of transactions ROLLBACK. This architecture need to be use with care if you have highly transactional workload that can generate cross shard deadlocks.

What are the most used architecture for spider HA?

Delegation of shard node replication using asynchronous replication and slave election with GTID . Delegation of shard node replication via active passive HA solutions. Shard builds via replication into spider tables is interesting when you can route READS to a pool of spiders nodes reattaching the shards.

What are the most used architecture for spider Map Reduce?

Map reduce in Spider is limited to single table, building spider on top of some views can eliminate the need to eliminate joins Replication to universal tables to every shard is commonly used to enable the views on each shard

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