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https://issues.apache.org/jira/browse/CONNECTORS-55?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12886704#action_12886704
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Robert Muir commented on CONNECTORS-55:
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Karl, just quoting from the docs here. From my experience, i had no perf
problems in the past getting hsqldb to use my indexes, but my queries were
relatively simple (just lots of data).
bq. Because the queue may be very large, and this query may potentially return
ALL records in the queue, the query plan MUST wind up reading directly out of
the priority index, or the query simply will not work. It simply cannot afford
to read 20 million records into memory and then sort them!
HyperSQL can use an index on an ORDER BY clause if all the columns in ORDER BY
are in a single-column or multi-column index (in the exact order). This is
important if there is a LIMIT n (or FETCH n ROWS ONLY) clause. In this
situation, the use of index allows the query processor to access only the
number of rows specified in the LIMIT clause, instead of building the whole
result set, which can be huge. This also works for joined tables when the ORDER
BY clause is on the columns of the first table in a join. Indexes are used in
the same way when ORDER BY ... DESC is specified in the query. Note that unlike
other RDBMS, HyperSQL does not create DESC indexes. It can use any index for
ORDER BY ... DESC.
> Bundle database server with LCF packaged product
> ------------------------------------------------
>
> Key: CONNECTORS-55
> URL: https://issues.apache.org/jira/browse/CONNECTORS-55
> Project: Lucene Connector Framework
> Issue Type: Improvement
> Components: Framework core
> Reporter: Jack Krupansky
>
> The current requirement that the user install and deploy a PostgreSQL server
> complicates the installation and deployment of LCF for the user. Installation
> and deployment of LCF should be as simple as Solr itself. QuickStart is great
> for the low-end and basic evaluation, but a comparable level of simplified
> installation and deployment is still needed for full-blown, high-end
> environments that need the full performance of a ProstgreSQL-class database
> server. So, PostgreSQL should be bundled with the packaged release of LCF so
> that installation and deployment of LCF will automatically install and deploy
> a subset of the full PostgreSQL distribution that is sufficient for the needs
> of LCF. Starting LCF, with or without the LCF UI, should automatically start
> the database server. Shutting down LCF should also shutdown the database
> server process.
> A typical use case would be for a non-developer who is comfortable with Solr
> and simply wants to crawl documents from, for example, a SharePoint
> repository and feed them into Solr. QuickStart should work well for the low
> end or in the early stages of evaluation, but the user would prefer to
> evaluate "the real thing" with something resembling a production crawl of
> thousands of documents. Such a user might not be a hard-core developer or be
> comfortable fiddling with a lot of software components simply to do one
> conceptually simple operation.
> It should still be possible for the user to supply database server settings
> to override the defaults, but the LCF package should have all of the
> best-practice settings deemed appropriate for use with LCF.
> One downside is that installation and deployment will be platform-specific
> since there are multiple processes and PostgreSQL itself requires a
> platform-specific installation.
> This proposal presumes that PostgreSQL is the best option for the foreseeable
> future, but nothing here is intended to preclude support for other database
> servers in futures releases.
> This proposal should not have any impact on QuickStart packaging or
> deployment.
> Note: This issue is part of Phase 1 of the CONNECTORS-50 umbrella issue.
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