Details
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Type:
Story
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Status: Done
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Resolution: Done
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Fix Version/s: None
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Component/s: Qserv
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Labels:None
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Epic Link:
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Team:Data Access and Database
Description
Qserv should support the following type of queries:
-- Create a binary representation of the search polygon
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SET @poly = scisql_s2CPolyToBin(359.9601, 2.5952,
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0.0398, 2.5952,
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0.0398, 2.6748,
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359.9601, 2.6748);
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-- Compute HTM ID ranges for the level 20 triangles overlapping
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-- @poly. They will be stored in a temp table called scisql.Region
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-- with two columns, htmMin and htmMax
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CALL scisql.scisql_s2CPolyRegion(@poly, 20);
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-- Select reference objects inside the polygon. The join against
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-- the HTM ID range table populated above cuts down on the number of
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-- SimRefObject rows that need to be tested against the polygon
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SELECT refObjectId, isStar, ra, decl, rMag
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FROM SimRefObject AS sro INNER JOIN
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scisql.Region AS r ON (sro.htmId20 BETWEEN r.htmMin AND r.htmMax)
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WHERE scisql_s2PtInCPoly(ra, decl, @poly) = 1;
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This 3-step process can be hidden inside qserv, without exposing it to user. Ideally, we should be able to run it behind the scene, and avoid changing/extending the existing API between user and the proxy
This story has been transfered from https://dev.lsstcorp.org/trac/ticket/2056
Attachments
Activity
Ping. I think this is supposed to be done already, right?
This has been supported for a good while now.
Comment by Daniel made in 2013:
It should be a lot easier to expose a syntax like this to the user:
SELECT refObjectId, isStar, ra, decl, rMagFROM SimRefObjectWHERE qserv_areaspec_poly(359.9601, 2.5952,0.0398, 2.5952,0.0398, 2.6748,359.9601, 2.6748) = 1;Note: Since the scheme relies on an htmId20 column, there is no choice for ra/decl columns anyway--htmId20 is always used.
This is preferable since it's much harder to support all of the syntax required to make the original 3-step approach work from the user. Those 3 steps can be generated programatically, but implementing new language syntax is much harder, especially if you want it to work in a distributed context.
Hiding it is probably a week's work (or less), once the scisql workings are understood. It could take a bit more time to discover the failure modes and to make those happen reasonably.