Re: refreshRow is slow - Mailing list pgsql-jdbc

John T. Dow wrote:

> Following that, where my program would do the refreshRow on the original resultset, I find a 21 instances of this
block(some lines omitted): 
>
> 17:25:50.812 (1) simple execute, handler=org.postgresql.jdbc2.AbstractJdbc2Statement$StatementResultHandler@1142196,
maxRows=0,fetchSize=0, flags=17 
> 17:25:50.812 (1)  FE=> Parse(stmt=null,query="SELECT attname FROM pg_catalog.pg_attribute WHERE attrelid = $1 AND
attnum= $2",oids={23,23}) 
> 17:25:50.812 (1)  FE=> Bind(stmt=null,portal=null,$1=<16404>,$2=<1>)

This is a metadata query, getting the canonical name of each
field/column in your resultset so that updateRow() knows how to build
the refresh query.

> 17:38:47.031 (1) selecting select id, address, citystatezip, combined, degree, email, fax, firstname, groupname,
lastname,nfiid, pabsid, practicetype, ssn, telephone, insertby, insertdate, inserttime, updateby, updatedate,
updatetimefrom doctor where id= ? 
> 17:38:47.046 (1) simple execute, handler=org.postgresql.jdbc2.AbstractJdbc2Statement$StatementResultHandler@d3c6a3,
maxRows=0,fetchSize=0, flags=17 
> 17:38:47.046 (1)  FE=> Parse(stmt=null,query="select id, address, citystatezip, combined, degree, email, fax,
firstname,groupname, lastname, nfiid, pabsid, practicetype, ssn, telephone, insertby, insertdate, inserttime, updateby,
updatedate,updatetime from doctor where id= $1",oids={1043}) 
> 17:38:47.046 (1)  FE=> Bind(stmt=null,portal=null,$1=<0984>)
> 17:38:47.046 (1)  FE=> Describe(portal=null)
> 17:38:47.046 (1)  FE=> Execute(portal=null,limit=0)
> 17:38:47.046 (1)  FE=> Sync

And this is the actual refreshRow() query. I assume that this WHERE
clause looks correct for your table and that query should be pretty fast?

> To me, who knows nothing, the mystery is why 21 repetitions?

21 columns.

> I repeated this with another table. The original query had 792 rows. I went to the last row and made a change. This
timethere were 408 repetitions. Again, it used the primary key for the $1 parameter shown above. 
>
> So why 408 repetitions this time?

408 columns. Is this a very wide SELECT?

I can see that 408 roundtrips would slow things down a lot over a
high-latency connection such as over the internet. Perhaps that's the
cause of the slowdown you see..

-O