AvailHalos

Such tables list all the snapshots for which FOF, BDM, and/or BDM halo profile information is available in the corresponding database.

If data is not available, the data column contains a ‘NULL’ value, otherwise it contains either a shortcut (e.g. ‘F’ for FOF) or, for the newer simulations (MDPL), an integer for the number of halos that are available at the given timestep.

The specific columns vary for each simulation; but each of them represents one of the data result sets.

Column Type UCD Unit Description
snapnum smallint time.epoch number of snapshot
redshift double time.epoch corresponding redshift
FOF char(1) or int availability of FOF halo catalog (value of this field is ‘F’ or the number of FOF groups when available, otherwise it is NULL).
BDM char(1) or int availability of BDM halo catalog (value of this field is ‘B’ or the number of halos when available, otherwise it is NULL).
BDMprof char(2) or int availability of BDM halo profiles (value of this field is ‘BP’ or the number of halos when available, otherwise it is NULL).

Example

Please note that the DISTINCT keyword is used here, since this small table is replicated on each node and we want to avoid duplicate results.

Get a list of all snapshots for which FOF catalogs are available in the MDR1 simulation:

SELECT DISTINCT * FROM MDR1.AvailHalos
WHERE FOF='F' ORDER BY snapnum

Get the snapshots for which BDM data exists for the MDPL simulation:

SELECT DISTINCT * FROM MDPL.AvailHalos
WHERE BDM IS NOT NULL ORDER BY snapnum

Get the number of available FOF1-halos for each snapshot from the MDPL simulation:

SELECT DISTINCT snapnum, FOF1 FROM MDPL.AvailHalos
WHERE FOF1 IS NOT NULL ORDER BY snapnum

This information is only available for simulations from MDPL on; for MDR1 and Bolshoi one needs to count the halos manually. This can be done directly in the database like this (use long queue for such queries!):

SELECT COUNT(*) as num FROM MDR1.FOF5
GROUP BY snapnum ORDER BY snapnum

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