predicate.md

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