Package sqlannotation provides functions for annotating DML statements with keyspace-id comments and parsing them. These annotations are used during filtered-replication to route the DML statement to the correct shard. TOOD(erez): Move the code for the "_stream" annotations from vttablet to here.
Possible values for ExtractKeySpaceIDError.Kind
AddKeyspaceIDs returns a copy of 'sql' annotated with the given keyspace id. It also appends the additional marginComments, if any.
AnnotateIfDML annotates 'sql' based on 'keyspaceIDs'
If 'sql' is not a DML statement no annotation is added. If 'sql' is a DML statement and contains exactly one keyspaceID
it is used to annotate 'sql'
Otherwise 'sql' is annotated as replication-unfriendly.
ExtractKeyspaceIDS parses the annotation of the given statement and tries to extract the keyspace id. If a keyspace-id comment exists 'keyspaceID' is set to the parsed keyspace id and err is set to nil; otherwise, if a filtered-replication-unfriendly comment exists or some other parsing error occured, keyspaceID is set to nil and err is set to a non-nil error value.
ExtractKeySpaceIDError is the error type returned from ExtractKeySpaceID Kind is a numeric code for the error (see constants below) and Message is an error message string.