Predicate pushdown support

Predicate structure

Currently, VAST Database allows pushing down filter predicate p of the following logical structure:

• An AND between multiple column predicates: p = p1 & p2 & p3

• Within each column predicate pi, an OR between range predicates: ci = r1 | r2 | r3 | r4

• Each range predicate rj is one of the following operators (where "x" is a column name, and c is a constant):

  • comparison operator:

    • t["x"] < c

    • t["x"] <= c

    • t["x"] == c

    • t["x"] > c

    • t["x"] >= c

    • t["x"] != c

  • is_in operator:

    • t["x"].isin([c1, c2, c3, c4, c5])

  • NULL checking:

    • t["x"].isnull()

    • ~t["x"].isnull()

  • Prefix match:

    • t["x"].startswith("prefix")

  • Substring match:

    • t["x"].contains("substr")

Column types

The following Arrow types support predicate pushdown:

• int8

• int16

• int32

• int64

• float32

• float64

• utf8

• bool

• decimal128

• binary

• date32

• time32

• time64

• timestamp