Questions tagged [shared-buffers]
The shared-buffers tag has no usage guidance.
15
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Why is PostgreSQL reading from heap and how to improve cache usage?
I have an SQL query that executes slowly on PostgreSQL 13.15 with 128GB of memory. The query mainly performs a Bitmap Heap Scan, and I’ve noticed that many reads are coming from the heap instead of ...
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51
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PostgreSQL: Is there any way to differentiate an actual Disk I/O from system cache hit?
When using EXPLAIN with buffers, the blocks read sometimes are actually from system cache, this is understandable sometimes based on the read time. But is there any proper way to understand a system ...
- 341
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Postgresql tuning
We have migrated our PROD DB to new server with 24GB RAM.
Based on that value it is possible to tune some PG configuration values?
I think we can increase some values.
Is it possible to suggest which ...
- 141
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208
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What is the root cause of 'out of shared memory ' issue?
I'm having 'out of shared memory' issue in PostgreSQL 13.3 on x86_64-pc-linux-gnu (The database has 41G data), first, it suggested me to increase max_locks_per_transaction.
After increasing ...
- 125
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234
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effective_cache_size vs shared_buffers
What is the difference between effective_cache_size and shared_buffers ?
I got confused .While we trying to query on a table (like select) what happens to query? what role do the effective_cache_size ...
- 1
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357
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Shared buffers, WAL buffers and Checkpointers
I am taking this EDB PostgreSQL essential course and Instructor explained about PostgreSQL architecture referring to the diagram that, whenever a client make an update request and suppose data is ...
- 123
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85
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What is a good test command to cause Postgres to use/fill shared_buffers?
I am doing testing on a replica, trying to diagnose why servers take several minutes to shutdown when fast mode is used. It seems to correlate with high shmem usage, can anyone recommend a good query ...
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459
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Does it make sense to enlarge "shared_buffers" for writing Postgresql?
I'm using Postgresql-11, with a traditional HDD as the physical storing device.
I need to optimize the performance for writing.
I have changed the wal_buffers from -1 to 512MB, that means that ...
- 357
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1k
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PostgreSQL size of used shared buffer vs actual result size
I am debugging a production issue where a regular index scan used in a join reports very high buffers usage (sometimes gigabytes) when inspecting using explain (analyse, buffers). Because it's reading ...
- 3
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144
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pg_prewarm like funcationality in MySQL
I know in Postgres, we can explicitly load a table into the cache using pg_prewarm extension, is there a similar mechanism/UDF/etc in MySQL? I know MySQL would cache data in shared buffer implicitly, ...
- 11
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493
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Exclude tables from shared_buffers in postgres
Is there a way to exclude tables from being added to the shared_buffers?
I've looked at the space used by the tables and those which use the most are not really relevant for us at the moment. There ...
- 121
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AWS Aurora PostgreSQL Serverless: How do you pre-warm the shared buffer after scaling?
I'm using AWS Aurora PostgreSQL Serverless with autoscaling.
It appears as though scaling clears the shared buffer, so right when we want to crank out the performance, we are forced to face-plant with ...
- 163
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14k
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Postgres 10 Query waits on IO: BufFileWrite causing failure to get new database connections
I have a query (attached with query plan) that is run every 5-7 seconds from every device that is running our dashboard (typically, 500+ devices at peak time). This query, at the outset looks like it ...
- 201
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831
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PostgreSQL. Shared_memory and sessions
I have a standalone server which is running Jira and PostgreSQL 9.6. I have noticed that PostgreSQL has shared_buffers parameter is equal 128MB where RAM is 32GB. Because server is shared with ...
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Why is PostgreSQL reporting a higher shared_buffers value than the parameter in the configuaration file when trying to enable huge_pages?
On a 7.5 GB host (Ubuntu 16.04.5 LTS), I have allocated 3 GB to shared_buffers:
postgres=# SHOW shared_buffers;
shared_buffers
----------------
3GB
(1 row)
with:
postgres@my-host:~$ cat /etc/...
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