Support IS DISTINCT

[gregorymfoster]

Describe the bug

Error raised when upserting using Typeorm.

To Reproduce

typescript:

async function upsertOrgs(orgs: Organization[], connection: DataSource) {
  await connection
    .createQueryBuilder()
    .insert()
    .into(GithubOrg)
    .values(
      orgs.map((org) => {
        const orgEntity = new GithubOrg();
        orgEntity.githubId = org.id;
        orgEntity.githubLogin = org.login;
        orgEntity.name = org.name || "";
        orgEntity.avatarURL = org.avatarUrl;
        return orgEntity;
      })
    )
    .orUpdate(["name", "avatarURL", "githubLogin"], ["githubId"], {
      // typeorm's version of upsert
      skipUpdateIfNoValuesChanged: true,
    })
    .execute();
}

Error output:

     QueryFailedError: 💔 Your query failed to parse.
This is most likely due to a SQL syntax error. However, you might also have hit a bug, or an unimplemented feature of pg-mem.
If this is the case, please file an issue at https://github.com/oguimbal/pg-mem along with a query that reproduces this syntax error.

👉 Failed query:

    INSERT INTO "github_org"("id", "githubId", "githubLogin", "name", "avatarURL", "createdAt", "updatedAt") VALUES ('C5aR4nTlebRqTmM7agZc', '2', 'org2_login', 'org2', 'google.com', DEFAULT, DEFAULT), ('vjFuYovcIvHAk6n5dNEz', '3', 'org3_login', 'org3', 'google.com', DEFAULT, DEFAULT) ON CONFLICT ( "githubId" ) DO UPDATE SET "name" = EXCLUDED."name", "avatarURL" = EXCLUDED."avatarURL", "githubLogin" = EXCLUDED."githubLogin"  WHERE ("github_org"."name" IS DISTINCT FROM EXCLUDED."name" OR "github_org"."avatarURL" IS DISTINCT FROM EXCLUDED."avatarURL" OR "github_org"."githubLogin" IS DISTINCT FROM EXCLUDED."githubLogin")  RETURNING "createdAt", "updatedAt";

💀 Syntax error at line 1 col 455:

  INSERT INTO "github_org"("id", "githubId", "githubLogin", "name", "avatarURL", "createdAt", "updatedAt") VALUES ('C5aR4nTlebRqTmM7agZc', '2', 'org2_login', 'org2', 'google.com', DEFAULT, DEFAULT), ('vjFuYovcIvHAk6n5dNEz', '3', 'org3_login', 'org3', 'google.com', DEFAULT, DEFAULT) ON CONFLICT ( "githubId" ) DO UPDATE SET "name" = EXCLUDED."name", "avatarURL" = EXCLUDED."avatarURL", "githubLogin" = EXCLUDED."githubLogin"  WHERE ("github_org"."name" IS DISTINCT
                                                                                                                                                                                                                                                                                                                                                                                                                                                                        ^
Unexpected kw_distinct token: "distinct". Instead, I was expecting to see one of the following:

    - A "kw_null" token
    - A "kw_not" token
    - A "kw_not" token
    - A "kw_true" token
    - A "kw_false" token


      at PostgresQueryRunner.query (node_modules/typeorm/driver/postgres/PostgresQueryRunner.js:211:19)
      at async InsertQueryBuilder.execute (node_modules/typeorm/query-builder/InsertQueryBuilder.js:106:33)

pg-mem version

2.3.5

[gregorymfoster]

Thanks in advance for taking a look!