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clarifications
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@aljoscha
aljoscha committed Feb 2, 2024
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11 changes: 7 additions & 4 deletions doc/developer/design/20231127_pv2_logical_architecture.md
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Expand Up @@ -386,10 +386,13 @@ synthesizes `AdvanceCatalogFrontier` commands when the catalog timestamp
advances. These commands are the commands that deterministically derive from
CATALOG state (see Background section, above).

When processing client requests, ADAPTER uses TIMESTAMP ORACLE to get the
latest read timestamp for CATALOG, then fetches a CATALOG snapshot as of at
least that timestamp, and continues to process the request using the catalog
snapshot as the source of truth.
When processing client requests, ADAPTER uses TIMESTAMP ORACLE to get the latest
read timestamp for CATALOG, then fetches a CATALOG snapshot as of at least that
timestamp, and continues to process the request using the catalog snapshot as
the source of truth. It's important to note that the catalog timestamp is not
correlated with the timestamp of data collections that are being queried. Most
of the time, the catalog read timestamp will not advance, it will only advance
when DDL cause the catalog to change.

When handling DDL-style client queries, ADAPTER uses TIMESTAMP ORACLE to get a
write timestamp and tries to append the required changes to the CATALOG. If
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