duplicate_cursor (SQLSTATE 42P03) is raised when you declare a cursor with a name that already exists in the current session or transaction block.
PostgreSQL duplicate_cursor (42P03) arises when a DECLARE command tries to create a cursor that already exists in the active transaction. Close or deallocate the previous cursor, or choose a unique name, to resolve the issue.
PostgreSQL Error 42P03
PostgreSQL throws duplicate_cursor (SQLSTATE 42P03) when a DECLARE statement attempts to create a cursor with a name already open in the current session or transaction.
The server enforces unique cursor names to avoid ambiguity during FETCH, MOVE, and CLOSE operations.
Reusing a name without closing the prior cursor violates this rule and halts execution.
Reissuing DECLARE with the same cursor name in a function, DO block, or psql script triggers the error immediately after the second declaration.
Running parallel sessions in a single connection pool that reuse static cursor names also causes collisions, especially in long-lived transactions.
Always CLOSE or DEALLOCATE a cursor before redeclaring it.
Alternatively, generate unique cursor names with dynamic SQL or transient identifiers.
If your application reuses connections, wrap cursor work in a transaction block and issue COMMIT to auto-close unnamed cursors.
Looping PL/pgSQL functions that forget to CLOSE cursors leak names; add a BEGIN…EXCEPTION…END block to guarantee closure even on error.
Interactive psql sessions often copy DECLARE statements; simply run CLOSE my_cur; before the new DECLARE.
Adopt consistent cursor-naming conventions and suffix names with timestamps or UUIDs to prevent duplication.
Use PostgreSQL portals via RETURNING queries when possible; they eliminate manual cursor management.
Error 42P01 (undefined_table) signals missing relations referenced by the cursor query; create or qualify the table.
Error 34000 (invalid_cursor_name) appears when FETCH or CLOSE targets a nonexistent cursor; confirm the name or scope.
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A script issues two DECLARE statements with the identical cursor name before COMMIT or ROLLBACK, causing an immediate conflict.
A function declares a cursor inside a loop but forgets to CLOSE it, so the next iteration collides with the existing cursor.
Long-lived pooled connections keep cursors open between requests; subsequent clients unknowingly reuse the same names.
Developers manually rerun DECLARE statements in interactive shells without closing the prior cursor.
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Yes. All cursors opened inside a transaction are closed on COMMIT or ROLLBACK, preventing duplicate_cursor in later transactions.
Cursor names are scoped to the current session. Two separate connections can use the same name without conflicts.
CLOSE releases the cursor but keeps prepared statements if any. DEALLOCATE removes both the cursor and its planned statement.
Galaxy's AI copilot detects existing cursors in your session and auto-suggests CLOSE commands, minimizing manual oversight.
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