I become crazy i not understand why After a fresh backup/restore, on this table
CREATE TABLE DESCRIPTIONS ( IDObj VARCHAR(15) NOT NULL, type SMALLINT NOT NULL, Lang VARCHAR(3) NOT NULL, Descr VARCHAR(10000), PRIMARY KEY (IDObj, type, Lang) ); and a foreign key on IDOBJ with 32 Millions rows, then select IDObj from description where IDObj=randomID with 50 simultaneous thread, take around 480 ms to return With 1 Thread, take around 34 ms to return Indexed Read: 125 Non Indexed Read: 0 BUT on this table CREATE TABLE IDREL ( ID1 SMALLINT NOT NULL, ID2 SMALLINT NOT NULL, ID3 INTEGER NOT NULL, KEY BIGINT NOT NULL, IDObject VARCHAR(15), PRIMARY KEY (ID1,ID2,ID3,KEY)); and a FOREIGN KEY on IDObject with 48 Millions rows, then select IDObj from IDREL where IDObj=randomID with 50 simultaneous thread, take around 40 ms to return !! With 1 Thread, take around 3.7 ms to return !! Indexed Read: 150 Non Indexed Read: 0 So 10x more faster !! but their is more rec in the table IDREL i even force plan to use the index on the IDObj Foreign key, nothing change :( i m lost lost lost :( the speed stay the same Blob instead of varchar(10000): CREATE TABLE DESCRIPTIONS ( IDObj VARCHAR(15) NOT NULL, type SMALLINT NOT NULL, Lang VARCHAR(3) NOT NULL, Descr BLOB SUB_TYPE 1 SEGMENT SIZE 4096, PRIMARY KEY (IDObj, type, Lang) ); still 10x more slower than the table IDREL --- In [email protected], "nathanelrick" <nathanelrick@...> wrote: > > hello, > > i do some more tests to investigate ... > > * When the table is read only by a single user (or very few user) speed is > fast (around 30 ms by select) > > * when the table is read by more users (around 50), then the speed go down ! > around 500 ms by select > > * When the table is also updated by some writer, then the speed completely > fall down, 1200 ms by select :( > > But on other table, with even more records, same amount of select / insert / > update / seconds, but without any varchar(10000) field then speed stay always > around 13 ms > > So > > remembered the table is simply : > > CREATE TABLE DESCRIPTIONS > ( > IDObj VARCHAR(15) NOT NULL, > type SMALLINT NOT NULL, > Lang VARCHAR(3) NOT NULL, > Descr VARCHAR(10000), > PRIMARY KEY (IDObj, type, Lang) > ); > > Why a varchar(10000) field (if it's because of the varchar(10000) field, > still not sure) can slow down so much the select ? remembered than even > select ... where id not exist => also 1200 ms ! > > what i can do to speed it up ? > > > > > > --- In [email protected], "nathanelrick" <nathanelrick@> wrote: > > > > hello, > > > > the table : > > > > CREATE TABLE DESCRIPTIONS > > ( > > IDObj VARCHAR(15) NOT NULL, > > type SMALLINT NOT NULL, > > Lang VARCHAR(3) NOT NULL, > > Descr VARCHAR(10000), > > PRIMARY KEY (IDObj, type, Lang) > > ); > > > > With around 40 millions records > > > > now the query : > > > > select Descr From DESCRIPTIONS where (IDObj='XXX') AND (type = 1) > > > > => 1200 ms to return only one reccord :( > > the speed is the same if xxx not exist ! > > > > the plan used: > > PLAN (DESCRIPTIONS INDEX (RDB$PRIMARY135)) > > > > what is wrong ? > > > > on some other table with around the same number of rec but no > > VARCHAR(10000) field then the return is in around 40 ms ! > > >
