sql: permit creation and refreshing of materialized views as of system time #56167
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Previously, running a statement of the form
CREATE TABLE t AS SELECT ... FROM ... AS OF SYSTEM TIME x
was not supported.
Now, it is supported. The semantics are that the table creation happens
at the transaction timestamp, but the backfill that's performed to fetch
the data from the `SELECT` is performed at the user-specified timestamp
x.
This is useful for copying data from tables that are experiencing write
traffic. Reading the contended table's data at a historical timestamp
avoids contention on the CREATE TABLE AS.
Release note (sql change): CREATE TABLE AS SELECT ... FROM ... AS OF
SYSTEM TIME x is now supported.
Add the ability to CREATE and REFRESH MATERIALIZED VIEWS, AS OF SYSTEM TIME. The purpose of this is to allow the expensive backfill operations to happen at a timestamp in the past to avoid contention. Currently, this is a little bit broken, because schema changes of the backing tables of the views can wreak havoc when performed at different system times. Release note (sql change): add AOST capabilities to materialized views.
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Depends on #55916.
Add the ability to CREATE and REFRESH MATERIALIZED VIEWS, AS OF SYSTEM
TIME. The purpose of this is to allow the expensive backfill operations
to happen at a timestamp in the past to avoid contention.
Currently, this is a little bit broken, because schema changes of the
backing tables of the views can wreak havoc when performed at different
system times.
Release note (sql change): add AOST capabilities to materialized views.