Informix Error -861

Reasons / Common Causes

-861 fires when the server can't create a new thread for Parallel Database Query (PDQ) processing — per the official guidance, the accompanying ISAM error carries the specific reason.

1. An underlying ISAM-level error during thread creation, per the official guidance's pointer to checking the accompanying ISAM error — the only documented path to the specific cause.
2. A system-wide thread/process limit reached, plausible given the general nature of PDQ parallelism (it spawns multiple threads per query), though not explicitly named by the sparse official text.
3. PDQPRIORITY/decision-support memory configuration insufficient for the requested degree of parallelism, another plausible category given the PDQ-specific context.

Solutions / Resolution

1. Check the accompanying ISAM error code, per the official guidance — the only documented path to the specific underlying cause.
2. Check system-wide thread/process limits if the ISAM error points toward a resource exhaustion condition, similar to -722's stack-space and -826's fork-failure patterns.
3. Review PDQPRIORITY and decision-support memory configuration (DS_TOTAL_MEMORY, MAX_PDQPRIORITY) if PDQ-specific resource limits seem implicated.

Examples

Checking the accompanying ISAM error

-- Review the ISAM error code reported alongside -861 for the specific
-- underlying reason PDQ thread creation failed.

Diagnostic Checks

1. Check the accompanying ISAM error code first, per the official guidance.
2. Check system-wide thread/process limits and PDQ-related configuration if the ISAM error points toward resource exhaustion.

Related Errors / Related Topics

• -722 — "Out of stack space." A related resource-exhaustion error, at the per-thread stack level rather than PDQ thread creation itself.

Check the accompanying ISAM error first, then system-wide thread limits and PDQ-related configuration if resource exhaustion is suspected.