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Questions tagged [wal]

WAL, or write-ahead log, is a form of journalling used as part of crash-safety and atomic commit support in databases like PostgreSQL and SQLite.

PostgreSQL's write-ahead log is a crucial feature that permits crash-safety and atomic commit to be implemented. It's also heavily used in PostgreSQL's point-in-time recovery, streaming replication, and archive based replication features, as well as hot physical backup.

In SQLite, the default method by which SQLite implements atomic commit and rollback is a rollback journal. Beginning with version 3.7.0, a new "Write-Ahead Log" option (hereafter referred to as "WAL") is available.

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How to show the WAL status in PHP?

My PHP code: $db = new PDO("sqlite:$dbname"); $db->exec("PRAGMA journal_mode = WAL;"); How do I show the status of WAL e.g. "echo....."? Thx in advance for your hints.
josefus
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PostgreSQL 12 WAL archive, WAL file restore

I see another questions about this but not clear or working for me. I have one database PostgreSQL 12 version. I made one general backup approx 3 month ago, then turned on the WAL archive. Here is my config file ( some important…
Mr.Database
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PostgreSQL not creating new WAL at archive_timeout interval

I have set archive_timeout to 300 seconds (5 min). Yet WAL files remain open for a very long time (hours). My postgresql.conf file includes: archive_mode = on archive_timeout = 300 archive_command = '/usr/local/internal/pgarchive.sh "%p"…
TSG
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"Missing" column in Postgres logical replication update message

We have a replication slot set up on a database in Postgres 12.8. For one of the tables, when a row is created, we see a series of records come through - an insert followed by a handful of updates. All of these messages in the WAL files show all…
kvndm
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Store datapoints persistently before writing to database

I have a Django app that receives sensor data. This data is then processed and written to influxDB using the influxdb-client-python library. I would like to write the data in an asynchronous manner and thus return a response to the producer of the…
Willem Govaerts
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What will happen if write to memtable fails but write to commit log succeeds in Cassandra writes?

I have a question regarding the WAL + memtable writes in Cassandra. By default until WAL and memtable are both updated, Cassandra doesn't mark the write as complete. However, if the WAL succeeds and the memtable write fails, isn't Cassandra in…
user12331
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How to remove old WAL file in postgresql?

I am using postgresql database cluster. I have an issue with low disk space. After investigation I found it is happen due to WAL file. Due to WAL file my disc space reduce dramatically. Now I need to free up some space without loosing any data or…
Sheikh Wasiu Al Hasib
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Storing incremental changes in Azure postgresql database from prod server database

Background : I have my prod postgresql db on a remote server and another DB some other azure server. 2nd db has been restored with the full backup of prod db. I need to transfer all the latest changes in the 2nd DB which is on some other server. As…
ABHISHEK KUMAR SINGH
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Why the SQLite database file is locked using WAL Mode and Pooling enabled?

I am using a SQLite Database in my C# program. The program saves values every second in the DB, and also checks everytime if the tables already exist: class DataManager : IDataManager { private bool machineTableIsCreated = false; private…
Vini121
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Postgres walwriter and background writer using memory

I just did a large import of renderd tiles for an osm server. I want to start my next process (running the import of nominatim) but it takes a lot of memory. The problem I have is that walwriter, background writer, checkpointer are consuming 131GB…
Paul Toone
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Postgres System frozen in WALSync

I've hit this issue three times in a row now and I don't know what is causing it. Context: I am running large scripts and at some point the system gets stuck in a WALSync state. The best way to describe it is this view of…
Alexi Theodore
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AWS DMS task failing after some time in CDC mode

I'm having trouble in setting up a task migrating the data in a RDS Database (PostgreSQL, engine 10.15) into an S3 bucket in the initial migration + CDC mode. Both endpoints are configured and tested successfully. I have created the task twice, both…
MKS
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WALs getting pilled up - restart_lsn of logical replication not moving in PostgreSQL

We have a replication setup from AWS RDS PostgreSQL to Kafka. The replication slot's restart_lsn is not moving and WALs keep pilling up. I tried to remove all the Kafka replications and tried using logical replication and AWS DMS on the same…
Chetan Dev Khanna
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Are WALs containing large active transactions recycled after a checkpoint?

Are WALs containing large active (not committed) transactions recycled after a checkpoint ? I think yes but i'm not sure... Normally with MVC strategy not committed transactions are stored in new lines versions. So after a checkpoint active…
Christophe Leray
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HBase WAL replication - Is WAL replication from cluster with HBase 1.1.2 to cluster with HBase 2.0.2 supported?

Is HBase WAL replication from cluster with HBase 1.1.2 to cluster with HBase 2.0.2 supported ? Tried a simple test where following table was created in both the clusters create 'repl_test', { NAME => 'cf1', REPLICATION_SCOPE => '1'} When issued…
vmaroli
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