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Audit Log File Format

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Warning

As of the time of this publication, audit logging features are made available and licensed only as part of the SingleStore Enterprise edition.

Audit logs are written to the directory specified by the auditlogsdir variable. See Configure Audit Logging for details on how to set this variable.

Each node in a cluster will create its own files in the destination directory using the following naming convention:

auditlog_<hostname>-<port>_<year>-<month>-<day>_<hour>-<minute>-<second>.log

For example, consider the following log file name:

auditlog_myVmbox-3306_2016-08-30_06-38-46.log

If a log file’s rotation size is very small, an auto-incrementing integer may be appended to the end of the log file. For example:

auditlog_myVmbox-3306_2016-08-30_06-38-46_1.log
auditlog_myVmbox-3306_2016-08-30_06-38-46_2.log
auditlog_myVmbox-3306_2016-08-30_06-38-46_3.log

Data within the log file is written in comma-separated values (CSV) format. Log files are updated immediately as queries are executed; they are not cached locally and then eventually written to the destination directory.

The auditlog_disk_sync engine variable controls whether the audit is written to disk synchronously. This can be set to ON/OFF to specify synchronous/asynchronous writes to disk. Note that if it is set to ON (synchronous writes), there can be an impact to performance as log entries must be flushed to disk before the query executes.

Log Entry File Schemas

The following sections describe the corresponding record schema for each audit log type.

First Line Schema

The first line of a log file has a unique schema that describes the event or action that resulted in the creation of a new log file. It has the following schema:

<id>,<time>,INFO: <origin>. <version>. <action>

Field

Description

id

Represents the unique identifier for the log entry within the scope of a single log file. This value is always 0 for the first line in a log file.

time

Specifies the local system time when the file was opened or rotated, using the same timestamp formatting as other audit log records.

origin

Describes the reason or event that caused the creation of the log file. It can have the following values:

  • Log rotated: Indicates that a new file was required because rotation conditions were met. When a log is rotated, either the auditlog_rotation_size or the auditlog_rotation_time engine variable's conditions are met.

  • Log opened on MemSQL startup: Indicates that a new file was created because the node was either started or restarted.

version

Specifies current audit logging format version.

action

Describes the audit logging state associated with the new file. It can have the following values:

  • Log level initiated at <auditlog-level>: Indicates that audit logging was first enabled at a given level and then the log file was opened.

  • Log level changed to <auditlog-level>: Indicates that logging was already enabled, but the audit logging level was changed.

  • Logging at level <auditlog-level>: Indicates that the system was restarted or the log was rotated, but the audit log level remained the same.

For example:

0,2026-06-21 18:49:25.888,INFO: Log opened on MemSQL startup. Format version 4. Logging at level ADMIN-ONLY-INCLUDING-PARSE-FAILS

Login and Logout Schema

Each login attempt and logout event is logged using the following schema:

Note

The logout event log schema does not contain the authtype and status fields.

<id>,<time>,<timezone>,<endpoint>,<nodetype:agg|leaf>,<type:USER_LOGIN|USER_LOGOUT>,<threadid>,<username>,<remotehost>,<usergrant:grant_user@grant_host>,<authtype>,<status:SUCCESS|FAILURE: reason>,<tlscipher>,<appname>,<osuser>

Field

Description

id

Represents the unique identifier for the log entry within the scope of a single log file.

time

Specifies the node’s local system time when an operation was executed.

timezone

Specifies the local time zone when the event was logged.

endpoint

Specifies the hostname or IP address of the SingleStore cluster in the <host>:<port> format.

nodetype

Specifies the type of node. It can have one of the following values:

  • agg: For aggregators.

  • leaf: For leaf nodes.

type

Specifies the login or logout event type. It can have the following values:

  • USER_LOGIN: For login attempts.

  • USER_LOGOUT: For logout event.

threadid

Specifies the ID of the thread that is running the statement.

username

Specifies the username of the user performing the login or logout.

remotehost

Specifies the hostname or IP address that the client is using to connect to the cluster. This value is detected by the server and not reported by the client.

usergrant

Specifies the 'username'@'hostname' specification from the GRANT that defines the user being authenticated or logged out.

authtype

(Login attempts only)

Specifies the authentication method for the user, for example, password, PAM, Kerberos, etc.

status

(Login attempts only)

Indicates the success or failure of the login attempt. It can have the following values:

  • SUCCESS: For a successful login.

  • FAILURE: reason: For a failed login attempt. Optionally, includes a reason that specifies why the login attempt failed.

tlscipher

Specifies the TLS encryption algorithm used during the session.

appname

Specifies the client application name retrieved from the session's program_name attribute, if set.

osuser

Specifies the client OS user retrieved from the session's _os_user attribute, if set.

For example:

363750385,2026-08-11 18:53:18.150,UTC,c770dd909a9c:3306,agg,USER_LOGIN,100000,s2user,192.168.0.1,s2user@%,mysql_native_password,SUCCESS,ECDHE-RSA-AES256-GCM-SHA384,mysql,osuser

Completion Record Schema for Query Execution

Completion records capture the final outcome of a query after execution. They are emitted as a separate record, associated with the original query record by id. Completion records have the following schema:

<id>,<record_type>,<completion_status:SUCCESS|FAILURE:error_code>,<records_affected>

Field

Description

id

Specifies the audit-log record ID of the original query record, used to correlate the command completion log to the original query.

record_type

A record-type marker which indicates a query record. Its value is always C for a completion record.

status

Specifies the final status of the query. It can have the following values:

  • SUCCESS: Indicates successful execution of the query.

  • FAILURE:<error_code>: Indicates query failure and includes the error returned by the SingleStore engine.

records_affected

Specifies the number of affected or returned records recorded at completion time.

For example:

123456,C,SUCCESS,42

Schema for ALL-RESULTS Database Responses

If your node is configured to use the ALL-RESULTS logging mode, the database’s responses are logged uniquely from other entries. Consider the following example result entry for the SHOW VARIABLES LIKE '%master_aggregator%' query:

237,R,master aggregator

The log entry above demonstrates the following schema:

<parent-query-log-entry-id>,R,<data>

Query results share the same entry ID as the query itself. In the example above, the log entry for the query also has an <entry-id> value of 237. The comma-separated R denotes that the log entry only contains query result data. Lastly, the returned data is included as the last value in the entry.

General Log Entry Schema

All entries in a log file adhere to a predefined schema. To help understand the log file schema, consider the following example entry for the statement UPDATE t SET a = 0 WHERE a = 1:

237,2016-08-25 11:29:09,PDT,localhost:3306,agg,1,99999,root,db,temp_1_14_16,9959767090931131257,UPDATE t SET a = 0 WHERE a = 1

The log entry above demonstrates the following schema:

<log-entry-id>,<timestamp>,<time-zone>,<hostname>:<port>,<node-type>,<aggregator-id>,<thread-id>,<username>,<database-name>,<correlation-id>,<query-hash>,<query>

Therefore, each of the 12 values can be mapped in the following way:

Example Value

Definition

237

log-entry-id

2016-08-25 11:29:09.875

timestamp

PDT

time-zone

localhost:3306

hostname:port

agg

node-type

1

aggregator-id

99999

thread-id

root

username

db

database-name

temp_1_14_16

correlation-id

9959767090931131257

query-hash

UPDATE t SET a = 0 WHERE a = 1

query

log-entry-id

The first value is log-entry-id, which represents the entry’s unique identifier within the scope of a single log file. Every new file always starts with an entry that has an ID of 0, incrementing by one afterwards. A log-entry-id is a 64-bit unsigned integer value.

The entry ID for any given operation is unique to the node, regardless of how a query is processed across the cluster. For example, imagine a three node cluster with a master aggregator and two leaves. When the master aggregator receives a distributed query and executes it on both leaf nodes, each leaf’s entry ID for the operation may be completely different.

If your database is configured to use the ALL-RESULTS logging mode, the results will appear as additional log entries with the same <log-entry-id> as the parent. For more information, see Schema for ALL-RESULTS Database Responses.

timestamp

The second value is timestamp, which specifies the node’s local system time when an operation was executed. The timestamp is printed in %Y-%m-%d %H:%M:%S.%f format.

time-zone

The third value is time-zone, which specifies the local time zone when an operation was executed. The time zone is printed as an initialism, such as GMT (Greenwich Mean Time).

hostname:port

The fourth value is hostname:port, which specifies the node’s hostname and port. The hostname is the same the database’s hostname global variable. Together, these values represent the identifier for a node.

node-type

The fifth value is node-type, which specifies whether the node is an aggregator (agg) or a leaf (leaf).

aggregator-id

The sixth value is aggregator-id, which specifies the ID of the aggregator that issued any given query. An aggregator-id is a 64-bit unsigned integer value.

An aggregator-id may contain an invalid value of 18446744073709551615 if the aggregator has not yet been given an ID.

In a cluster with multiple aggregators, the ID of the master aggregator never changes, but the ID of a child aggregator may change. For example, if a child aggregator temporarily loses network connectivity and then reconnects, it may acquire a new aggregator ID. The child aggregators that remained connected might also have their aggregator IDs altered during the event.

When correlating a master aggregator’s query with its resulting downstream leaf node queries, you can use the combination of an entry’s correlation-id and aggregator-id values as a unique identifier. For example, if a query is executed against a cluster with one master aggregator and one leaf node, the query will be logged in the master aggregator’s log file and the leaf node’s log file. To quickly correlate entries for the same query across large log files, use the combination of the correlation-id and aggregator-id as a key.

thread-id

The seventh value is thread-id, which specifies the ID of the node’s thread that is executing the query. A thread-id is a 32-bit integer value.

username

The eight value is username, which specifies the username of the authenticated user who is executing the query.

database-name

The ninth value is database-name, which specifies the name of the database that is being queried.

This value may appear as [unknown] in a log entry under a few conditions:

  • If the query is not related to a specific database (e.g. SHOW VARIABLES).

  • If the user does not specify USE <database-name> before executing their query. However, in this case the query does contain the database, such as SELECT * from <db-name>.t.

correlation-id

The tenth value is correlation-id, which specifies an identifier for the current query. Multiple successive log entries can reference the same correlation-id, especially when a query requires data from more than one leaf partition.

When correlating a master aggregator’s query with its resulting downstream leaf node queries, you can use the combination of an entry’s correlation-id and aggregator-id values as a unique identifier. For example, if a query is executed against a cluster with one master aggregator and one leaf node, the query will be logged in the master aggregator’s log file and the leaf node’s log file. To quickly correlate entries for the same query across large log files, use the combination of the correlation-id and aggregator-id as a key.

Under some circumstances, a correlation-id value may not appear in the log entry. This value is usually missing when a DDL operation is executed.

query-hash

The 11th value is query-hash, which specifies a unique hash of either the query signature or the query text. The query-hash is a 64-bit unsigned integer value.

The full query text will only be hashed if the node’s logging level is set to ALL-QUERIES-PLAINTEXT or ALL-QUERIES-PLAINTEXT-INCLUDING-PARSE-FAILS. Otherwise, just the query signature will be hashed.

query

The 12th value is the query, which specifies either the query signature or the query text.

The full query text will only be written to the log if the node’s logging level is set to ALL-QUERIES-PLAINTEXT or ALL-QUERIES-PLAINTEXT-INCLUDING-PARSE-FAILS. Otherwise, just query signature will be hashed.

The USING clause of queries is not captured as part of audit logging and can be viewed via SHOW PROCESSLIST where applicable.

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Verification instructions

Note: You must install cosign to verify the authenticity of the SingleStore file.

Use the following steps to verify the authenticity of singlestoredb-server, singlestoredb-toolbox, singlestoredb-studio, and singlestore-client SingleStore files that have been downloaded.

You may perform the following steps on any computer that can run cosign, such as the main deployment host of the cluster.

  1. (Optional) Run the following command to view the associated signature files.

    curl undefined

  2. Download the signature file from the SingleStore release server.

    • Option 1: Click the Download Signature button next to the SingleStore file.

    • Option 2: Copy and paste the following URL into the address bar of your browser and save the signature file.

    • Option 3: Run the following command to download the signature file.

      curl -O undefined

  3. After the signature file has been downloaded, run the following command to verify the authenticity of the SingleStore file.

    echo -n undefined |
        cosign verify-blob --certificate-oidc-issuer https://oidc.eks.us-east-1.amazonaws.com/id/CCDCDBA1379A5596AB5B2E46DCA385BC \
          --certificate-identity https://kubernetes.io/namespaces/freya-production/serviceaccounts/job-worker \
          --bundle undefined \
          --new-bundle-format -
    Verified OK

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