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  1. MariaDB Server
  2. MDEV-8368

CONNECT engine mysql table type require a table level lock every time when inserting

        Details

        • Type: Task
        • Status: Open
        • Priority: Minor
        • Resolution: Unresolved
        • Fix Version/s: None
        • Component/s: Storage Engine - Connect
        • Labels:
          None

          Description

          It causes the delay on high concurrency insertion.

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                bertrandop Olivier Bertrand added a comment -

                Can you elaborate and give an example?
                What are the source and remote table like and what is the insert command?
                Thanks.

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                bertrandop Olivier Bertrand added a comment - Can you elaborate and give an example? What are the source and remote table like and what is the insert command? Thanks.
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                serg Sergei Golubchik added a comment -

                I suspect the original reporter uses “mysql” table type to connect to an InnoDB table. InnoDB supports row-level locks, so perhaps the CONNECT table that connects to InnoDB might use row-level locks too.

                Currently CONNECT always uses table-level locks, see ha_connect::store_lock. For row-level locks, this method needs to downgrade table locks to TL_WRITE_ALLOW_WRITE, see how complex ha_innobase::store_lock is.

                May be you can do no locking for “mysql” table type at all — and rely on the locks on the underlying table. Or may be not, I'm not sure it'll work.

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                serg Sergei Golubchik added a comment - I suspect the original reporter uses “mysql” table type to connect to an InnoDB table. InnoDB supports row-level locks, so perhaps the CONNECT table that connects to InnoDB might use row-level locks too. Currently CONNECT always uses table-level locks, see ha_connect::store_lock . For row-level locks, this method needs to downgrade table locks to TL_WRITE_ALLOW_WRITE, see how complex ha_innobase::store_lock is. May be you can do no locking for “mysql” table type at all — and rely on the locks on the underlying table. Or may be not, I'm not sure it'll work.
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                bertrandop Olivier Bertrand added a comment -

                What does FEDERATED about locking? It should be interresting to compare the difference between CONNECT and FEDERATED in high concurrency insertion.

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                bertrandop Olivier Bertrand added a comment - What does FEDERATED about locking? It should be interresting to compare the difference between CONNECT and FEDERATED in high concurrency insertion.
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                serg Sergei Golubchik added a comment -

                See ha_federatedx::store_lock(). It downgrades the lock to TL_WRITE_ALLOW_WRITE and sometimes to TL_READ.

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                serg Sergei Golubchik added a comment - See ha_federatedx::store_lock() . It downgrades the lock to TL_WRITE_ALLOW_WRITE and sometimes to TL_READ.

                  People

                  • Assignee:
                    bertrandop Olivier Bertrand
                    Reporter:
                    tramchamploo tramchamploo
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                    Dates

                    • Created:
                      Updated: