Hi,
just a "wild" guess: WAL (write ahead log) not flushed, yet?
IMHO there is no (easy) way to check that (outside the MonetDB kernel)
Stefan
----- On Jul 31, 2018, at 5:43 PM, Roberto Cornacchia roberto.cornacchia@gmail.com wrote:
> Hi,
>
> We are having a problem, for a while, that is difficult to isolate.
>
> Our ETL includes the following steps:
>
> 1) Open JDBC connection, add data to a table, commit, close connection
> 2) Open JDBC connection, some ALTER TALBLE statements, commit, close connection
>
> Occasionally, we get the following during step 2) :
>
> java.sql.SQLException: ALTER TABLE: set READ or INSERT ONLY not possible with
> outstanding updates (wait until updates are flushed)
> at
> nl.cwi.monetdb.jdbc.MonetConnection$ResponseList.executeQuery(MonetConnection.java:2732)
>
> What puzzles me is that step one is completed when this happens, the commit is
> done and the connection is closed (we triple-checked that is actually is
> closed).
>
> Notice that inserting a sleep between the to steps makes it work correctly.
>
> As I said, this is hard to isolate and reproduce. Still, can anyone guess what
> is exactly happening?
> Can it be that a background process is still flushing updates from step 1) ?
> Even if the JDBC connection is closed ?
> Can we force a blocking flush, so that it doesn't return until it's safe?
> If not, how can we know when updates are flushed?
>
> Thanks, Roberto
>
>
>
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