Informix Error -510

Reasons / Common Causes

-510 fires when CREATE SYNONYM targets a temporary table — synonyms are a persistent schema object, and Informix doesn't allow one to point at a table that only exists for the current session.

1. CREATE SYNONYM issued against a temp table, per the official guidance — the direct, only cause.
2. A misspelled table name that happens to collide with an existing temp table's name, when a permanent table was actually intended.
3. Application code that creates a synonym as a convenience alias, not realizing the underlying table is session-scoped temporary rather than permanent.

Solutions / Resolution

1. Review the spelling of the table name, per the official guidance, in case a permanent table was intended instead.
2. Redesign the application, per the official guidance, by either:
   • Making the table permanent (CREATE TABLE instead of CREATE TEMP TABLE) if it needs a synonym, or
   • Not using a synonym and referencing the temp table by its real name directly, since synonyms aren't necessary within the single session a temp table lives in anyway.

Examples

The disallowed attempt

CREATE TEMP TABLE staging_orders (order_id INT, status CHAR(10));
CREATE SYNONYM so FOR staging_orders;
-- -510: staging_orders is a temporary table

Working around it — reference the temp table directly

CREATE TEMP TABLE staging_orders (order_id INT, status CHAR(10));
SELECT * FROM staging_orders;  -- no synonym needed within the same session

Or make it a permanent table if a synonym is genuinely required

CREATE TABLE staging_orders (order_id INT, status CHAR(10));
CREATE SYNONYM so FOR staging_orders;

Diagnostic Checks

1. Confirm whether the table is temporary before attempting to create a synonym for it — a synonym is a durable catalog object and a temp table by definition isn't durable across sessions.

Related Errors / Related Topics

• -508 — "Cannot rename a temporary table." The same temp-table restriction applied to renaming instead of synonym creation.
• -509 — "Cannot rename a column in a temporary table." The same restriction applied to column renames.

A synonym is a persistent catalog object pointing at a session-scoped temp table doesn't make sense — make the table permanent, or skip the synonym and reference it directly.