Hi Ramin, Thank you for for driving this topic.
I have a couple of questions about this proposal： 1. Could we elaborate a bit more on when users would typically need this feature? It will be helpful to have a few concrete scenarios illustrating. 2. Since the proposal supports converting a CatalogTable to a CatalogMaterializedTable, should we also consider the reverse direction? I'd appreciate your thoughts on this. Kui.Yuan On Wed, May 13, 2026 at 12:58 PM Ramin Gharib <[email protected]> wrote: > Hi everyone, > > I'd like to start a discussion on FLIP-578: In-place Table to Materialized > Table conversion. [1] > Flink's catalog DDL has no way to change a table's kind. Converting a > regular CREATE TABLE to a materialized table today requires creating a new > MT under a different name, repointing downstream consumers, and dropping > the old one — breaking references, doubling storage during cutover, and > offering no atomic rename. > > The FLIP proposes to allow CREATE OR ALTER MATERIALIZED TABLE > <existing_table> AS <query> against an existing regular table, converting > it in place. Identity and storage are preserved, and the conversion > surfaces as a distinct Operation subtype. > > Highlights: > 1. Gated by a new opt-in config option, > table.materialized-table.conversion-from-table.enabled (default false). > Existing workflows are unchanged. > 2. A new Catalog method convertTableToMaterializedTable(...) is added with > a default that throws UnsupportedOperationException, so existing catalogs > remain source- and binary-compatible. > 3. Validation reuses the existing ALTER MATERIALIZED TABLE machinery > (schema reconciliation, options merge, freshness / refresh-mode). The > CREATE OR ALTER keyword (FLIP-546 [2]) is idempotent and inherits FLIP-492 > query evolution for free. > > Looking forward to your feedback. > > Best, > Ramin Gharib [1] > > https://urldefense.com/v3/__https://cwiki.apache.org/confluence/display/FLINK/FLIP-578*3A*In-place*Table*to*Materialized*Table*conversion__;JSsrKysrKw!!Ayb5sqE7!okBJoaLkkG9CS-7XJ5l20-eJBddTSHhZHynnZ7xdXeAhOZrvdFXf09dnUUyaJIYySkEuoby00NK9xierjHTyPQ$ > [2] > > https://urldefense.com/v3/__https://cwiki.apache.org/confluence/display/FLINK/FLIP-546*3A*Introduce*CREATE*OR*ALTER*for*Materialized*Tables__;JSsrKysrKys!!Ayb5sqE7!okBJoaLkkG9CS-7XJ5l20-eJBddTSHhZHynnZ7xdXeAhOZrvdFXf09dnUUyaJIYySkEuoby00NK9xicxCTyQDA$ >
