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| author | Peter Eisentraut <peter@eisentraut.org> | 2019-04-08 13:47:46 +0200 |
|---|---|---|
| committer | Peter Eisentraut <peter@eisentraut.org> | 2019-04-08 13:47:46 +0200 |
| commit | 348f57ce5be96190491e2153abb47060884f8ebf (patch) | |
| tree | 85d669010ec9bfec3f0cb4b8efb9df52f8fa9b10 | |
| parent | 119dcfad988d5b5d9f52b256087869997670aa36 (diff) | |
| download | postgresql-348f57ce5be96190491e2153abb47060884f8ebf.tar.gz postgresql-348f57ce5be96190491e2153abb47060884f8ebf.zip | |
doc: Add note about generated columns in foreign tables
Explain that it is not enforced that querying a generated column
returns data that is consistent with the data that was stored. This
is similar to the note about constraints nearby.
Reported-by: Amit Langote <amitlangote09@gmail.com>
| -rw-r--r-- | doc/src/sgml/ref/create_foreign_table.sgml | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/doc/src/sgml/ref/create_foreign_table.sgml b/doc/src/sgml/ref/create_foreign_table.sgml index 6b15726517e..5db15eb73eb 100644 --- a/doc/src/sgml/ref/create_foreign_table.sgml +++ b/doc/src/sgml/ref/create_foreign_table.sgml @@ -351,6 +351,16 @@ CHECK ( <replaceable class="parameter">expression</replaceable> ) [ NO INHERIT ] </para> <para> + Similar considerations apply to generated columns. Stored generated + columns are computed on insert or update on the local + <productname>PostgreSQL</productname> server and handed to the + foreign-data wrapper for writing out to the foreign data store, but it is + not enforced that a query of the foreign table returns values for stored + generated columns that are consistent with the generation expression. + Again, this might result in incorrect query results. + </para> + + <para> While rows can be moved from local partitions to a foreign-table partition (provided the foreign data wrapper supports tuple routing), they cannot be moved from a foreign-table partition to another partition. |