Bug #2154
closed
Metacat Performace: Configurable path condition indices
Added by Saurabh Garg almost 19 years ago.
Updated over 18 years ago.
Description
From Matt's email...
Configurable path condition indices -- this would allow admins to
configure specific XML paths in metacat to be replicated to their own
table in the DB (which would be dynamically created) to make searching
fast for those paths. This is effective because clients (e.g., Morpho,
web) tend to use only a limited set of where clause restrictions (e.g.,
on title, surname, keyword, ...). In a typical EML document with 5000
nodes, our current search has to hit many records when searching for a
path like "dataset/title". Given that each document has only one or a
few titles, a dedicated table for title that is indexed might only have
3500 records in the "dataset/title" table (compared to ~106 in
xml_nodes), which would be a significantly faster query. Also, by
creating temporary tables for all commonly searched fields, we would
possibly avoid searchcing the xml_nodes table altogether, and therefore
avoid the whole recursive query issue. See Sid's point #2 below for
more details. This has a lot of potential for speeding up structured
queries (e.g., spatial), but xml_nodes would still be used for
unstructured (anyfield) queries.
From my email:
Metacat can have a new index table for admin specified fields. This will be
helpful as both xml_nodes and xml_index are huge tables. But most of the
queries we run are on a few specific fields. Example: any search on NCEAS skin
results in the following query:
((SELECT DISTINCT docid FROM xml_nodes WHERE UPPER LIKE '%NATIONAL
CENTER FOR ECOLOGICAL ANALYSIS AND SYNTHESIS%' AND parentnodeid IN (SELECT
nodeid FROM xml_index WHERE path LIKE 'organizationName') )) Instead, lets say
we have a metacat where the user has specified in metacat.properties that
organizationName should be indexed seperately. Then we can replace the above
query with something like this:
SELECT DISTINCT docid FROM xml_indexed_path WHERE nodedata LIKE '%NATIONAL
CENTER FOR ECOLOGICAL ANALYSIS AND SYNTHESIS%' AND path LIKE 'organizationName')
xml_indexed_path could be a table which has three simple fields - docid,
nodedata and path where nodedata and path are indexed.
This is similar to adding nodedata column in xml_index table which I tried to
do in release 1.5. But I had to remove the changes because 1) The performance
gain was not that significant. 2) nodedata in xml_index was not an exact copy
of nodedata from xml_nodes because of space constraints.
However a new index table should result in 1) significant performance gain as
the query is one table and on a much smaller table. 2) nodedata in new table
would be exact copy of nodedata in xml_nodes. 3) user can tune metacat for the
queries paths which are important for him. e.g. organizationName, keywords,
coverage information, terms used in advanced search etc
Number of documents in KNB
database:
1600
Size of xml_index in current KNB
database:
3877202
Size of xml_index in current KNB
database:
5675990
Size of new table assuming we index 100 values/document for 1600
documents: 160000
(I think, 100 is easily an assumption on the higher side as far as
values/document is concerned)
It will also speed up queries like the following which are used while creating
the doclist...
select xml_nodes.docid, xml_index.path, xml_nodes.nodedata,
xml_nodes.parentnodeid from xml_index, xml_nodes where
xml_index.nodeid=xml_nodes.parentnodeid and (xml_index.path
like 'originator/individualName/surName' or xml_index.path
like 'originator/individualName/givenName' or xml_index.path
like 'originator/organizationName' or xml_index.path
like 'creator/individualName/surName' or xml_index.path
like 'creator/organizationName' or xml_index.path like 'dataset/title' or
xml_index.path like 'keyword' ) AND xml_nodes.docid in
('tonelow13.1024','Sartwell.88','ArchivalTag.5') AND xml_nodes.nodetype = 'TEXT
Done. Closing the bug as it is working fine.
Original Bugzilla ID was 2154
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