[YSQL] Avoid sending multiple Perform RPC simultaneously #12327
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Yugabyte SQL (YSQL)
kind/enhancement
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d-uspenskiy
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May 17, 2022
Summary: In context of the #11886 issue optimization for using tserver's read time has been introduced. This optimization may work incorrectly in case YSQL runs multiple `Perform` RPC simultaneously. `PgClientService` analyzes number of tablets which will be used by first read request in the transaction. In case of read from single tablet read time will be selected by tablet's tserver and in case of read multiple tablets read time will be selected locally. Running multiple `Perform` RPCs simultaneously may break the mechanism of choosing read time because each of the `Perform` RPC may read from single tablet by actually read will be performed from multiple tablets. For optimization purposes in case of foreign key check reading from multiple tables in parallel was introduced in context of the #11470 issue. Current version sends multiple `Perform` RPCs simultaneously. Current diff preserves reading from multiple tables in parallel by uses single `Perform` RPCs for this purpose. Test Plan: New unit test is introduced ``` ./yb_build.sh --gtest_filter PgFKeyTest.MultipleFKConstraintRPCCount ./yb_build.sh --gtest_filter PgFKeyTest.InsertWithLargeNumberOfFK ``` Reviewers: sergei, alex, lnguyen Reviewed By: lnguyen Subscribers: ssong, yql Differential Revision: https://phabricator.dev.yugabyte.com/D16751
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May 26, 2022
…mic table split Summary: In context of the change D16751 / 4e11189 redundant sorting of ybctids (before calling of the `PgDocOp::PopulateDmlByYbctidOps` method) was removed. But this change highlighted the problem that in case ybctids is not sorted read result might be incomplete in case of dynamic table split. The issue #12648 is created to solve the problem and create unit tests. Current change restores code with ybctids sorting as a workaround to unblock TPC-C benchmark. Test Plan: Jenkins Unit test will be added withing the context of fix for #12648 Reviewers: lnguyen Reviewed By: lnguyen Subscribers: smishra, yql Differential Revision: https://phabricator.dev.yugabyte.com/D17142
lnguyen-yugabyte
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May 28, 2022
…in case of dynamic table split Summary: Original commit: D17142 / 17f7b80 In context of the change D16751 / 4e11189 redundant sorting of ybctids (before calling of the `PgDocOp::PopulateDmlByYbctidOps` method) was removed. But this change highlighted the problem that in case ybctids is not sorted read result might be incomplete in case of dynamic table split. The issue #12648 is created to solve the problem and create unit tests. Current change restores code with ybctids sorting as a workaround to unblock TPC-C benchmark. Test Plan: Jenkins Unit test will be added withing the context of fix for #12648 Reviewers: dmitry, hbhanawat, rthallam Reviewed By: rthallam Subscribers: yql, smishra Differential Revision: https://phabricator.dev.yugabyte.com/D17251
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Jira Link: [DB-397](https://yugabyte.atlassian.net/browse/DB-397)
Description
In context of #11886 issue optimization for using tserver's read time has been introduced.
This optimization may work incorrectly in case YSQL runs multiple
PerformRPC simultaneously.PgClientServiceanalyzes number of tablets which will be used by first read request in the transaction. In case of read from single tablet read time will be selected by tablet's tserver and in case of read multiple tablets read time will be selected locally.Running multiple
PerformRPCs simultaneously may break the mechanism of choosing read time because each of thePerformRPC may read from single tablet by actually read will be performed from multiple tablets.The text was updated successfully, but these errors were encountered: