OnlineDDL: skip GetSchema where possible #10107
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Signed-off-by: Shlomi Noach <2607934+shlomi-noach@users.noreply.github.com>
shlomi-noach
added
Type: Enhancement
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Description
In
ApplySchema, there is a check for big schema changes. This is a legacy check from a time when we did not support online DDL. Big-schema-changes is mostly skipped when there are online DDLs. However, one step is not skipped, which isGetSchema.Currently, we first
GetSchema, then iterate all DDLs, and for each DDL check if it is online or not, and if not - whether it is a "big change".When all DDLs are online, the
GetSchemastep is wasteful. It reads all tables with some metadata.In this PR, we first do a preliminary check to see whether there is at all any non-online DDL. If there is at least one non-online DDL, we proceed with
GetSchema. But if all DDLs are online - we skipGetSchemaaltogether.Related Issue(s)
Checklist