QueryPolicy Class

The latest servers support retries on individual data partitions. This feature is useful when a cluster is migrating and partition(s) are missed or incomplete on the first query attempt.

If the first query attempt misses 2 of 4096 partitions, then only those 2 partitions are retried in the next query attempt from the last key digest received for each respective partition. A higher default maxRetries is used because it's wasteful to invalidate all query results because a single partition was missed.

Default: null

This compression feature requires the Enterprise Edition Server.

Default: false

Default: LONG

Default: false

This field is not applicable to batch, scan or query commands.

Default: false

Default: null

Default: true

Default: 0 (issue requests to all server nodes in parallel)

maxRecords is only supported when query filter is null. maxRecords exists here because query methods will convert into a scan when the query filter is null. maxRecords is ignored when the query contains a filter.

Default: 0 (do not limit record count)

If maxRetries is exceeded, the command will abort with AerospikeException.Timeout.

WARNING: Database writes that are not idempotent (such as Add()) should not be retried because the write operation may be performed multiple times if the client timed out previous command attempts. It's important to use a distinct WritePolicy for non-idempotent writes which sets maxRetries = 0;

Default for write: 0 (no retries)

Default for read: 2 (initial attempt + 2 retries = 3 attempts)

Default for scan/query: 5 (6 attempts. See ScanPolicy() comments.)

Default: ONE

Default: SESSION

For example, if the most recent write had a TTL of 10 hours and read_touch_ttl_percent is set to 80, the next read within 8 hours of the record's end of life (equivalent to 2 hours after the most recent write) will result in a touch, resetting the TTL to another 10 hours.

Values:

• 0 : Use server config default-read-touch-ttl-pct for the record's namespace/set.
• -1 : Do not reset record TTL on reads.
• 1 - 100 : Reset record TTL on reads when within this percentage of the most recent write TTL.

Default: 0

Default: Use standard record parser.

Default: 5000

Default: SEQUENCE

If the key is sent on a read, the server will generate the hash digest from the key and vildate that digest with the digest sent by the client. Unless this is the explicit intent of the developer, avoid sending the key on reads.

Default: false (do not send the user defined key)

For backwards compatibility: If shortQuery is true, the query is treated as a short query and expectedDuration is ignored. If shortQuery is false, expectedDuration is used and defaults to LONG.

Default: false

The sleep only occurs on connection errors and server timeouts which suggest a node is down and the cluster is reforming. The sleep does not occur when the client's socketTimeout expires.

Reads do not have to sleep when a node goes down because the cluster does not shut out reads during cluster reformation. The default for reads is zero.

The default for writes is also zero because writes are not retried by default. Writes need to wait for the cluster to reform when a node goes down. Immediate write retries on node failure have been shown to consistently result in errors. If maxRetries is greater than zero on a write, then sleepBetweenRetries should be set high enough to allow the cluster to reform (>= 3000ms).

Default: 0 (do not sleep between retries)

If socketTimeout is zero and totalTimeout is non-zero, then socketTimeout will be set to totalTimeout. If both socketTimeout and totalTimeout are non-zero and socketTimeout > totalTimeout, then socketTimeout will be set to totalTimeout. If both socketTimeout and totalTimeout are zero, then there will be no socket idle limit.

If socketTimeout is not zero and the socket has been idle for at least socketTimeout, both maxRetries and totalTimeout are checked. If maxRetries and totalTimeout are not exceeded, the command is retried.

For synchronous methods, socketTimeout is the socket SendTimeout and ReceiveTimeout. For asynchronous methods, the socketTimeout is implemented using the AsyncTimeoutQueue and socketTimeout is only used if totalTimeout is not defined.

Default: 30000ms

When a command is stopped prematurely, the socket must be drained of all incoming data or closed to prevent unread socket data from corrupting the next command that would use that socket.

If a socket read timeout occurs and timeoutDelay is greater than zero, the socket will be drained until all data has been read or timeoutDelay is reached. If all data has been read, the socket will be placed back into the connection pool. If timeoutDelay is reached before the draining is complete, the socket will be closed.

Sync sockets are drained in the cluster tend thread at periodic intervals. timeoutDelay is not supported for async sockets.

Many cloud providers encounter performance problems when sockets are closed by the client when the server still has data left to write (results in socket RST packet). If the socket is fully drained before closing, the socket RST performance penalty can be avoided on these cloud providers.

The disadvantage of enabling timeoutDelay is that extra memory/processing is required to drain sockets and additional connections may still be needed for command retries.

If timeoutDelay were to be enabled, 3000ms would be a reasonable value.

Default: 0 (no delay, connection closed on timeout)

The totalTimeout is tracked on the client and sent to the server along with the command in the wire protocol. The client will most likely timeout first, but the server also has the capability to timeout the command.

If totalTimeout is not zero and totalTimeout is reached before the command completes, the command will abort with AerospikeException.Timeout.

If totalTimeout is zero, there will be no total time limit.

Default for scan/query: 0 (no time limit)

Default for all other commands: 1000ms