Limit of 1024 stream entries in the handler in DolphinDB subscription?

Question

n=1000000
tmpTrades = table(n:0, colNames, colTypes)
lastMinute = [00:00:00.000]
colNames = `time`sym`vwap
colTypes = [MINUTE,SYMBOL,DOUBLE]
enableTableShareAndPersistence(table=streamTable(n:0, colNames, colTypes), tableName="vwap_stream")
go

def calcVwap(mutable vwap, mutable tmpTrades, mutable lastMinute, msg){
tmpTrades.append!(msg)
curMinute = time(msg.time.last().minute()*60000l)
t = select wavg(price, qty) as vwap from tmpTrades where time < curMinute, time >= lastMinute[0] group by time.minute(), sym
if(t.size() == 0) return
vwap.append!(t)
t = select * from tmpTrades where time >= curMinute
tmpTrades.clear!()
lastMinute[0] = curMinute
if(t.size() > 0) tmpTrades.append!(t)
}
subscribeTable(tableName="trades_stream", actionName="vwap", offset=-1, handler=calcVwap{vwap_stream, tmpTrades, lastMinute}, msgAsTable=true)

This is what I wrote to subscribe to the stream. Even though the data ingested to the publishing table vwap_stream is 5000 records per batch, the maximum number ingested to the handler is still 1024. Is there a limit to the subscription?

Answer 1

You can modify the configuration parameter maxMsgNumPerBlock to specify the maximum number of records in a message block and the default value is 1024. For a standalone mode the configuration file is dolphindb.cfg, and for a clustered mode is cluster.cfg.