SDSS_DR8.SclTree table

The SclTree table provides parent IDs for superclusters at various density levels.

Table structure

ColumnTypeUCDUnitDescription
sclidintmeta.idsupercluster ID
dleveldecimal(3,1)stat.paramdensity level
parentidintmeta.idparent supercluster ID

Sample queries

  1. Find the parents of the supercluster Scl 544. The query returns the list of objects it merges into with the corresponding density levels.
    SELECT MAX(dlevel),parentid FROM SDSS_DR8.SclTree WHERE sclid=544 AND parentid!=sclid GROUP BY parentid 
    ORDER BY parentid DESC
  2. Select supercluster IDs which are children of the supercluster Scl 6.
    SELECT sclid FROM SDSS_DR8.SclTree WHERE parentid=6 and sclid!=parentid GROUP BY sclid
  3. Select supercluster IDs that have the same parent ID as Scl 27 at the density threshold D = 3.0. This can be accomplished with a subquery:
    SELECT sclid FROM SDSS_DR8.SclTree 
    WHERE dlevel=3.0 AND 
    parentid=(SELECT parentid FROM SDSS_DR8.SclTree WHERE sclid=27 AND dlevel=3.0)
  4. Select all columns from the Supercluster table for the superclusters found with the previous query, using the density threshold D = 5.0. Note the usage of nested subqueries.
    SELECT * FROM SDSS_DR8.Supercluster 
    WHERE dlevel=5.0 AND sclid IN (SELECT sclid FROM SDSS_DR8.SclTree
    WHERE dlevel=3.0 AND parentid=(SELECT parentid FROM SDSS_DR8.SclTree WHERE sclid=231 AND dlevel=3.0))