Better Together: Unifying Datalog and Equality Saturation

PLDI 2023, June 2023
  author = {
    Yihong Zhang and
    Yisu Remy Wang and
    Oliver Flatt and
    David Cao and
    Philip Zucker and
    Eli Rosenthal and
    Zachary Tatlock and
    Max Willsey
  title = {Better Together: Unifying Datalog and Equality Saturation},
  year = {2023},


We present egglog, a fixpoint reasoning system that unifies Datalog and equality saturation (EqSat). Like Datalog, it supports efficient incremental execution, cooperating analyses, and lattice-based reasoning. Like EqSat, it supports term rewriting, efficient congruence closure, and extraction of optimized terms.

We identify two recent applications–a unification-based pointer analysis in Datalog and an EqSat-based floating-point term rewriter–that have been hampered by features missing from Datalog but found in EqSat or vice-versa. We evaluate egglog by reimplementing those projects in egglog. The resulting systems in egglog are faster, simpler, and fix bugs found in the original systems.