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fix(oracle): re-run LOB queries after a failed define without ORA-01002 - #18
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A query with LOB columns is executed, then sent again to define them. When either step failed, the statement went back to the driver's cache still marked as needing a define: its next execution only sent the define and fetched from a cursor that was never executed (ORA-01002), and so did every later run of the same SQL in the session. The vendored driver now closes that cursor so the next run parses the statement again, and Show DDL uses the statement cache again. Closes #17
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… again When the server parses a query again (statistics feedback, new statistics), it describes the columns again on the next execution, LOB columns as CLOB/BLOB, while the cursor keeps its define and returns them as LONG with the rows. The vendored driver took that as a new LOB column and sent a define after the rows were fetched (ORA-01002). Like python-oracledb's _adjust_metadata, such a column now keeps its LONG type. Refs #17
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Closes #17
The first time a query with LOB columns runs, it takes two round trips: an execute that returns the column descriptions, then a second execute that defines the LOB columns (as text here). Temporary protocol traces on 23ai and 21c in CI (not part of this PR) showed two ways the vendored driver later sent a define-only execute on a cursor that had nothing left to fetch, which the server answers with ORA-01002 (fetch out of sequence):
_adjust_metadata. On a cursor that already ran, a column described as CLOB/BLOB whose previous type was string/LONG (or RAW/LONG RAW) keeps the LONG type and needs no define.get_dependent_ddlon a table without comments, or any error raised while the first rows are fetched). The statement went back to the cache still flagged as needing a define, so every later run sent only the define and failed. Fix: close that cursor so the next run parses again, as python-oracledb does after errors.Both fixes are in
src-tauri/vendor/oracledband recorded as patches 3 and 4 inLOWQUERY.md.first_texts(Show DDL) no longer usesexclude_from_cache().New test
oracle_clob_queries_run_repeatedlycovers:dbms_metadata.get_ddl,to_clob(...), and a table with CLOBs over 4000 characters (all rows, and the first row only with the cursor left open), 5 runs each, withdbms_stats.gather_table_stats(no_invalidate => false)before run 3 to force the re-describe; a CLOB query that fails with ORA-01476 twice, then succeeds 3 times; and Show DDL 5 times through the statement cache. Before the fixes it failed on both 23ai and 21c (run 3 after the invalidation, and run 2 after the failed define).CHANGELOG entry under [Unreleased]; it ships in 0.5.2 together with export/import.