DatumToHLC performs the conversion from a Datum to an HLC timestamp.

Eval evaluates the timestamp argument to an AS OF SYSTEM TIME query.

EvalSystemTimeExpr evaluates an Expr as a system time.

IsFollowerReadTimestampFunction determines whether the AS OF SYSTEM TIME clause contains a simple invocation of the follower_read_timestamp function.

TypeCheckSystemTimeExpr type checks an Expr as a system time.

AsOf is when the DatumToHLC() is used for an AS OF SYSTEM TIME statement.

FollowerReadTimestampExperimentalFunctionName is the name of the old "experimental_" function, which we keep for backwards compatibility.

FollowerReadTimestampFunctionName is the name of the function which can be used with AOST clauses to generate a timestamp likely to be safe for follower reads.

ReplicationCutover is when the DatumToHLC() is used for an ALTER VIRTUAL CLUSTER ..

ShowTenantFingerprint is when the DatumToHLC() is used for an SHOW EXPERIMENTAL_FINGERPRINTS FROM TENANT ..

Split is when the DatumToHLC() is used for a SPLIT statement.

WithMaxStalenessFunctionName is the name of the function that can be used with AOST clauses to generate a bounded staleness at a maximum interval.

WithMinTimestampFunctionName is the name of the function that can be used with AOST clauses to generate a bounded staleness at a fixed timestamp.

OptionAllowBoundedStaleness signifies Eval should not error if a bounded staleness query is found.

DatumToHLCUsage specifies which statement DatumToHLC() is used for.

EvalOption is an option to pass into Eval.