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https://issues.apache.org/jira/browse/DRILL-4729?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Kunal Khatua updated DRILL-4729:
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Reviewer: Chun Chang
> Add support for prepared statement implementation on server side
> ----------------------------------------------------------------
>
> Key: DRILL-4729
> URL: https://issues.apache.org/jira/browse/DRILL-4729
> Project: Apache Drill
> Issue Type: Sub-task
> Components: Metadata
> Reporter: Venki Korukanti
> Assignee: Venki Korukanti
> Fix For: 1.8.0
>
>
> Currently Drill JDBC/ODBC driver implements its own prepared statement
> implementation, which basically issues limit 0 query to get the metadata and
> then executes the actual query. So the query is planned twice (for metadata
> fetch and actual execution). Proposal is to move that logic to server where
> we can make optimizations without disrupting/updating the JDBC/ODBC drivers.
> * {{PreparedStatement createPreparedStatement(String query)}}.
> {{PreparedStatement}} object contains the following:
> ** {{ResultSetMetadata getResultSetMetadata()}}
> *** {{ResultsSetMetadata}} contains methods to fetch info about output
> columns of the query. What info these methods provide is given in this
> [spreadsheet|https://docs.google.com/spreadsheets/d/1A6nqUQo5xJaZDQlDTittpVrK7t4Kylycs3P32Yn_O5k/edit?usp=sharing].
> It lists the ODBC/JDBC requirements and what Drill will provided through
> object {{ResultsSetMetadata}}.
> *** Server can put more info here which is opaque to client and use it in
> server when the client sends execute prepared statement query request.
> Overload the current submit query API to take the {{PreparedStatement}}
> returned above.
> In the initial implementation, server side implementation of
> {{createPreparedStatement}} API is implemented as follows:
> * Runs the query with {{LIMIT 0}}, gets the schema
> * Convert the query into a binary blob and set it as opaque object in
> {{PreparedStatement}}.
> When the {{PreparedStatement}} is submitted for execution, reconstruct the
> query from binary blob in opaque component of {{PreparedStatement}} and
> execute it from scratch.
> Opaque component of the {{PreparedStatement}} is where we can save more
> information which we can use for optimizations/speedups.
> NOTE: We are not going to worry about parameters in prepared query in initial
> implementation. We can provide the functionality later if there is sufficient
> demand from Drill community.
> Changes in this patch are going to include protobuf messages, server side
> messages and Java client APIs. Native client changes are going to be tracked
> in a separate JIRA.
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