getPersistenceMeta

getPersistenceMeta(table)

table is a table object.

Get metadata of a persistent stream table.

Return a dictionary with the following keys:

• lastLogSeqNum: the latest log sequence number of raft log.

• sizeInMemory: the number of records in memory.

• asynWrite: whether to persist data with asynchronous mode.

• totalSize: the total number of records in the stream table.

• compress: whether to save compressed data.

• memoryOffset: the offset position of the first message in memory relative to all records in the stream table. memoryOffset = totalSize - sizeInMemory.

• sizeOnDisk: the number of records that have been persisted to disk.

• retentionMinutes: how long (in terms of minutes) the log file will be kept. The default value is 1440 minutes (1 day).

• persistenceDir: the path to the persistent data.

• hashValue: the identifier of the thread responsible for persisting the table to disk. If persistenceWorkerNum>1, hashValue may not be 0.

• diskOffset: the offset position of the first message on disk relative to all records in the stream table.

colName=["time","x"]
colType=["timestamp","int"]
t = streamTable(100:0, colName, colType);
enableTableShareAndPersistence(table=t, tableName=`st, cacheSize=1200000)
go;

for(s in 0:200){
   n=10000
   time=2019.01.01T00:00:00.000+s*n+1..n
   x=rand(10.0, n)
   insert into st values(time, x)
}

getPersistenceMeta(st);

// output
astLogSeqNum->-1
sizeInMemory->800000
asynWrite->true
totalSize->2000000
raftGroup->-1
compress->true
memoryOffset->1200000
retentionMinutes->1440
sizeOnDisk->2000000
persistenceDir->/dolphindb/server/streamPersistDir/st
hashValue->0
diskOffset->0