Sylvain Amrani wrote:
Hi list,
I've got an attribute that could contains very long strings (more than 150 chr). It's a string made of small tokens separated by spaces and slashes :
departmentUID: BA/BAC ANDL/BAPZ IDF/GRPT YVLN/CIE GN ST GERM...
The attibute is indexed with pres,eq,sub
When I search for small substrings like (departmentUID=*/GRPT*) it's fast and ok.
When I search for a long subset of the string, the query is _very_ long (many seconds) : (departmentUID=BA/BAC ANDL/BAPZ IDF/GRPT YVLN/CIE GN ST*)
The more the string is long, the more the answer is slow.
I can use very complex filters (&((|()())(|()()))... and the answer is very fast, unless I use a long string in it.
The backend is BDB (berkeley 4.2) Openldap is 2.2.26
Is this a BDB or an Openldap related issue ? Using subinitial or subany in the index slap.conf parameter did not solve the problem.
That's a feature of OpenLDAP in 2.2 and older; subinitial and subfinal queries only index up to 4 characters of the string you provide. The rest are ignored. So indexing is not narrowing down the search candidates very much, and the full filter has to get evaluated on a lot of extraneous entries.
You should upgrade to the current 2.3, which uses the entire input string on index lookups.
I found only one post in the archives related to a server were any query string with more than 3 characters makes slow answers. He was told to adjust :
index_substr_if_minlen index_substr_if_maxlen index_substr_any_len index_substr_any_step
But theses parameters are only available with openldap 2.3 and it doesn't seem to be exactly my problem (I've no differences between 2,3,4 or 5 characters query strings)
Thanks, Sylvain.