Use decoded hex string when calculating the keyspace ID

[mattlord]

Description

This is a follow-up to #9118

There we normalized the incoming x'A1' or 0xA1 string literal token that represents binary data as hex so that we can pass it on to MySQL as a BindVar.

However, this means that when calculating the Keyspace ID in the vindex functions we need to decode the value again (as we do when parsing the incoming query) so that we're doing the keyspace range check using a decoded representation of the bytes that end up being stored in the column in MySQL.

This is accomplished here and here by properly managing the HexVal and HexNum BindVars:

• The "raw" value (Value.val / Value.Raw() and its variants) is "internal" and represents what was seen in the SQL query (e.g. x'997902' or 0x997902)
• The ToBytes value (Value.ToBytes()) returns the bytes that mysql would return when querying the column (e.g. �y).
  For example:

  $ mysql -u root -h 127.0.0.1 --binary-as-hex=false mydb -e "drop table if exists varbt; create table varbt (c1 varbinary(100)); insert into varbt values (x'997902'),(0x997902); select c1, hex(c1) from varbt"
  +------+---------+
  | c1   | hex(c1) |
  +------+---------+
  | �y   | 997902  |
  | �y   | 997902  |
  +------+---------+
  

We then see the exact same results for the vindex functions using the x'A1' format seen before normalizing hex values.

🆕 With this PR we also add support for using the 0xA1 format with vindexes which did NOT work before:

• 11.0:

  $ mysql customer -e "select id, hex_keyspace_id, shard from customer.binary where id = 0x997901"
  ERROR 1105 (HY000) at line 1: unsupported: where clause for vindex function must be of the form id = <val> (rhs is not a value)
  
  $ mysql customer -e "select id, hex_keyspace_id, shard from customer.binary_md5 where id = 0x997901"
  ERROR 1105 (HY000) at line 1: unsupported: where clause for vindex function must be of the form id = <val> (rhs is not a value)
  
  $ mysql customer -e "select id, hex_keyspace_id, shard from customer.xxhash where id = 0x997901"
  ERROR 1105 (HY000) at line 1: unsupported: where clause for vindex function must be of the form id = <val> (rhs is not a value)
  

• This branch:

  $ mysql customer -e "select id, hex_keyspace_id, shard from customer.binary where id = 0x997901"
  +------+-----------------+-------+
  | id   | hex_keyspace_id | shard |
  +------+-----------------+-------+
  | �y  | 997901          | 80-   |
  +------+-----------------+-------+
  
  $ mysql customer -e "select id, hex_keyspace_id, shard from customer.binary_md5 where id = 0x997901"
  +------+----------------------------------+-------+
  | id   | hex_keyspace_id                  | shard |
  +------+----------------------------------+-------+
  | �y  | 2d2da332b59f56aeb235ecb36d639440 | -80   |
  +------+----------------------------------+-------+
  
  $ mysql customer -e "select id, hex_keyspace_id, shard from customer.xxhash where id = 0x997901"
  +------+------------------+-------+
  | id   | hex_keyspace_id  | shard |
  +------+------------------+-------+
  | �y  | ac29dcaa4a0b4527 | 80-   |
  +------+------------------+-------+
  

So now for vindexes we are properly treating x'A1' and 0xA1 as equivalent. This is proper because while the string literal in the SQL query differs the same bytes are stored in MySQL for both. You can see a complete user test here.

Related Issue(s)

Fixes: #9275

Checklist

• This PR should be backported to 12.0 for the next patch release or we need to revert Ensure that hex query predicates are normalized for planner cache #9145
• Tests were added here
• Documentation is not required

[mattlord]

Example vindex function results from 11.0 before we started normalizing hex values (after this PR main produces the same results):

$ mysql customer -e "select id, hex_keyspace_id, shard from customer.binary where id = x'997901'"
+------+-----------------+-------+
| id   | hex_keyspace_id | shard |
+------+-----------------+-------+
| �y  | 997901          | 80-   |
+------+-----------------+-------+

$ mysql customer -e "select id, hex_keyspace_id, shard from customer.binary_md5 where id = x'997901'"
+------+----------------------------------+-------+
| id   | hex_keyspace_id                  | shard |
+------+----------------------------------+-------+
| �y  | 2d2da332b59f56aeb235ecb36d639440 | -80   |
+------+----------------------------------+-------+

$ mysql customer -e "select id, hex_keyspace_id, shard from customer.xxhash where id = x'997901'"
+------+------------------+-------+
| id   | hex_keyspace_id  | shard |
+------+------------------+-------+
| �y  | ac29dcaa4a0b4527 | 80-   |
+------+------------------+-------+

$ mysql customer -e "select id, hex_keyspace_id, shard from customer.xxhash where id = \"hi there\""
+----------+------------------+-------+
| id       | hex_keyspace_id  | shard |
+----------+------------------+-------+
| hi there | 8b42c06c4e1344e4 | 80-   |
+----------+------------------+-------+

[frouioui]

It looks good to me! :)

Before merging, let's see if 61cb238 resolves @harshit-gangal 's comment

[mattlord]

Here's a full user test:

make docker_local && ./docker/local/run.sh

./201_customer_tablets.sh ; ./202_move_tables.sh ; sleep 10; ./203_switch_reads.sh ; ./204_switch_writes.sh ; ./205_clean_commerce.sh ; ./301_customer_sharded.sh ; ./302_new_shards.sh ; ./303_reshard.sh ; sleep 10; ./304_switch_reads.sh ; ./305_switch_writes.sh ; ./306_down_shard_0.sh

vtctlclient GetVSchema customer > /tmp/customer.json

vtctlclient ApplyVSchema -vschema "$(jq '. | .vindexes += {"binary":{"type":"binary"}} | .tables += {"btest":{"columnVindexes":[{"column":"id","name":"binary"}]}}' < /tmp/customer.json)" customer

mysql customer -e "create table btest (id varbinary(50), name varchar(50))"
mysql customer -e "insert into btest (id, name) values (0xF901, 'test'),(0x1901, 'test'),(x'1801', 'test'),(x'F801', 'test')"

mysql customer -e "select hex(id) from btest"
mysql customer/-80 -e "select hex(id) from btest"
mysql customer/80- -e "select hex(id) from btest"

Results:

vitess@7a8847da946f:/vt/local$ mysql customer -e "select hex(id) from btest"
+---------+
| hex(id) |
+---------+
| 1901    |
| 1801    |
| F901    |
| F801    |
+---------+
vitess@7a8847da946f:/vt/local$ mysql customer/-80 -e "select hex(id) from btest"
+---------+
| hex(id) |
+---------+
| 1901    |
| 1801    |
+---------+
vitess@7a8847da946f:/vt/local$ mysql customer/80- -e "select hex(id) from btest"
+---------+
| hex(id) |
+---------+
| F901    |
| F801    |
+---------+

[harshit-gangal]

LGTM

[deepthi]

Very well-written description. Thank you for taking the time to write it up along with the code changes.