We currently do not support MySQL's PIPES_AS_CONCAT and ANSI_QUOTES SQL modes and likely never will.
This is because Vitess' SQL evaluation engine needs to be able to parse the SQL queries so that in a sharded setup it can aggregate and combine the results from different MySQL instances. Its parser and evaluation engine can only deal with the standard MySQL dialect and options as ANSI_QUOTES or PIPES_AS_CONCAT interfere with that.
You may find that you can enable these SQL modes, but please be aware that your queries may return incorrect or unexpected results. We may also disable this option in the future.
We recommend to use CONCAT() and standard quotation instead.
For more information on MySQL compatibility please also see our documentation.