How to Resolve SQLServer max memory exceeded in PostgreSQL

How do I stop PostgreSQL from throwing "max memory exceeded" errors?

Tune memory parameters like work_mem and temp_file_limit to stop PostgreSQL sessions from exceeding the configured RAM limits and aborting.

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Description

Example H2

Example H3

Why does PostgreSQL report a “max memory exceeded” error?

The planner allocates RAM per sort, hash, or aggregate based on work_mem. When the actual data volume outgrows that budget and temp_file_limit is reached, PostgreSQL stops the query and returns an out-of-memory message similar to “max memory exceeded.”

How do I check current memory settings?

Run SHOW work_mem;, SHOW maintenance_work_mem;, and SHOW temp_file_limit;. Compare the results with the physical RAM and concurrent session count to spot unrealistic defaults.

How can I raise work_mem safely?

Increase work_mem only as high as the server can afford for each active backend. Use ALTER SYSTEM SET work_mem = '64MB';, then SELECT pg_reload_conf();. For one-off heavy reports, issue SET LOCAL work_mem = '512MB'; inside the transaction.

What if temp files explode instead of RAM?

Large on-disk sorts inflate base/pgsql_tmp. Raise temp_file_limit or refactor the query to process fewer rows at once. Use SET temp_file_limit = '10GB'; for a session-level override.

Can shared_buffers cause memory pressure?

Yes. If shared_buffers is set too high, the OS page cache shrinks, forcing swap. Keep shared_buffers around 25% of total RAM on dedicated database servers.

How do I find the query that blew up?

Enable log_min_error_statement = ERROR and log_temp_files = 0. PostgreSQL will write the failing SQL and the size of every temporary file, helping you pinpoint problem statements.

What other best practices help?

• Always qualify ORDER BY columns with indexes.
• Use multicolumn indexes to avoid large in-memory sorts.
• Break analytical jobs into smaller batches with LIMIT/OFFSET or window functions.
• Schedule heavy reports during off-peak hours.

Why How to Resolve SQLServer max memory exceeded in PostgreSQL is important

How to Resolve SQLServer max memory exceeded in PostgreSQL Example Usage


-- Large sales report requiring more RAM for sorting totals
BEGIN;
SET LOCAL work_mem = '512MB';
SELECT c.name,
       SUM(oi.quantity * p.price) AS customer_lifetime_value
FROM   Customers c
JOIN   Orders     o  ON o.customer_id = c.id
JOIN   OrderItems oi ON oi.order_id   = o.id
JOIN   Products   p  ON p.id          = oi.product_id
GROUP  BY c.name
ORDER  BY customer_lifetime_value DESC
LIMIT  50;
COMMIT;

How to Resolve SQLServer max memory exceeded in PostgreSQL Syntax


-- Increase session memory for a heavy report
SET LOCAL work_mem = '512MB';
SET LOCAL temp_file_limit = '15GB';

-- Persist a safe default at the instance level (requires superuser)
ALTER SYSTEM SET work_mem = '64MB';          -- per sort/hash
ALTER SYSTEM SET maintenance_work_mem = '1GB';
ALTER SYSTEM SET temp_file_limit = '5GB';    -- per backend
ALTER SYSTEM SET shared_buffers = '8GB';     -- 25% of 32 GB RAM

-- Apply changes without restart
SELECT pg_reload_conf();

Common Mistakes

Setting work_mem globally to several hundred megabytes assumes only one active session. With dozens of users, memory balloons and the OS swaps. Fix by multiplying work_mem by expected concurrency and adjusting downward.
Maxing shared_buffers to 75-80 % of RAM squeezes the OS cache, causing kernel swapping that mimics out-of-memory errors. Keep it near 25 % on dedicated servers.

Frequently Asked Questions (FAQs)

Does raising work_mem always help?

Only when the workload is dominated by sorts or hash joins. If queries are CPU-bound or disk-bound, increasing work_mem offers little benefit and can harm overall stability.

How do I monitor temp file usage?

Set log_temp_files = 0 to log every temporary file with its size. Tools like pgBadger aggregate these logs so you can identify memory-hungry queries.