Help Center/ GaussDB(DWS)/ More Documents/ Tool Guide (ME-Abu Dhabi Region) / DSC: SQL Syntax Migration Tool/ MySQL Syntax Migration/ Unique Indexes
Updated on 2022-06-13 GMT+08:00
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Unique Indexes

If MySQL unique indexes (constraints) and primary key constraints are used together during migration, OLAP distribution keys may become unavailable. Therefore, this scenario is not supported by DSC.

  1. If there is an inline unique index, DSC will delete it directly.

    Input

    CREATE TABLE IF NOT EXISTS `public`.`runoob_dataType_test`
(
  `id` INT PRIMARY KEY AUTO_INCREMENT,
  `name` VARCHAR(128) NOT NULL,
  UNIQUE (id ASC)
);

    Output

    CREATE TABLE "public"."runoob_datatype_test"
(
  "id" SERIAL PRIMARY KEY,
  "name" VARCHAR(128) NOT NULL
)
  WITH ( ORIENTATION = ROW, COMPRESSION = NO )
  NOCOMPRESS
  DISTRIBUTE BY HASH ("id");
  2. If there is a unique index created by ALTER TABLE, DSC will create a normal index based on GaussDB features.

    Input

    CREATE TABLE IF NOT EXISTS `public`.`runoob_alter_test`(
    `dataType1` int,
    `dataType2` FLOAT(10,2),
    `dataType3` DOUBLE(20,8)
)ENGINE=InnoDB DEFAULT CHARSET=utf8;

ALTER TABLE runoob_alter_test ADD UNIQUE idx_runoob_alter_test_datatype1(dataType1);
ALTER TABLE runoob_alter_test ADD UNIQUE INDEX idx_runoob_alter_test_datatype1(dataType2);
ALTER TABLE runoob_alter_test ADD UNIQUE KEY idx_runoob_alter_test_datatype1(dataType3);

CREATE TABLE IF NOT EXISTS `public`.`runoob_alter_test`(
    `dataType1` int,
    `dataType2` FLOAT(10,2),
    `dataType3` DOUBLE(20,8),
    `dataType4` TEXT NOT NULL,
    `dataType5` YEAR NOT NULL DEFAULT '2018',
    `dataType6` DATETIME NOT NULL DEFAULT '2018-10-12 15:27:33.999999'
)ENGINE=InnoDB DEFAULT CHARSET=utf8;

ALTER TABLE runoob_alter_test ADD CONSTRAINT UNIQUE idx_runoob_alter_test_datatype1(dataType1);
ALTER TABLE runoob_alter_test ADD CONSTRAINT UNIQUE INDEX idx_runoob_alter_test_datatype2(dataType2);
ALTER TABLE runoob_alter_test ADD CONSTRAINT UNIQUE KEY idx_runoob_alter_test_datatype3(dataType3);
ALTER TABLE runoob_alter_test ADD CONSTRAINT constraint_dataType UNIQUE idx_runoob_alter_test_datatype4(dataType4);
ALTER TABLE runoob_alter_test ADD CONSTRAINT constraint_dataType UNIQUE INDEX idx_runoob_alter_test_datatype5(dataType5);
ALTER TABLE runoob_alter_test ADD CONSTRAINT constraint_dataType UNIQUE KEY idx_runoob_alter_test_datatype6(dataType6);

    Output

    CREATE TABLE "public"."runoob_alter_test"
(
  "datatype1" INTEGER,
  "datatype2" FLOAT(10),
  "datatype3" FLOAT(20)
)
  WITH ( ORIENTATION = ROW, COMPRESSION = NO )
  NOCOMPRESS
  DISTRIBUTE BY HASH ("datatype1");

CREATE INDEX "idx_runoob_alter_test_datatype1" ON "public"."runoob_alter_test" ("datatype1");
CREATE INDEX "idx_runoob_alter_test_datatype1" ON "public"."runoob_alter_test" ("datatype2");
CREATE INDEX "idx_runoob_alter_test_datatype1" ON "public"."runoob_alter_test" ("datatype3");

CREATE TABLE "public"."runoob_alter_test"
(
  "datatype1" INTEGER,
  "datatype2" FLOAT(10),
  "datatype3" FLOAT(20),
  "datatype4" TEXT NOT NULL,
  "datatype5" VARCHAR(4) NOT NULL DEFAULT '2018',
  "datatype6" TIMESTAMP WITHOUT TIME ZONE NOT NULL DEFAULT '2018-10-12 15:27:33.999999'
)
  WITH ( ORIENTATION = ROW, COMPRESSION = NO )
  NOCOMPRESS
  DISTRIBUTE BY HASH ("datatype1");

CREATE INDEX "idx_runoob_alter_test_datatype1" ON "public"."runoob_alter_test" ("datatype1");
CREATE INDEX "idx_runoob_alter_test_datatype2" ON "public"."runoob_alter_test" ("datatype2");
CREATE INDEX "idx_runoob_alter_test_datatype3" ON "public"."runoob_alter_test" ("datatype3");
CREATE INDEX "idx_runoob_alter_test_datatype4" ON "public"."runoob_alter_test" ("datatype4");
CREATE INDEX "idx_runoob_alter_test_datatype5" ON "public"."runoob_alter_test" ("datatype5");
CREATE INDEX "idx_runoob_alter_test_datatype6" ON "public"."runoob_alter_test" ("datatype6");
  3. If there is a unique index created by CREATE INDEX, DSC will create a normal index based on GaussDB features.

    Input

    CREATE TABLE `public`.`test_index_table01` (
	`TABLE01_ID` INT(11) NOT NULL,
	`TABLE01_THEME` VARCHAR(100) NULL DEFAULT NULL,
	`AUTHOR_NAME` CHAR(10) NULL DEFAULT NULL,
	`AUTHOR_ID` INT(11) NULL DEFAULT NULL,
	`CREATE_TIME` INT NULL DEFAULT NULL,
	PRIMARY KEY(`TABLE01_ID`)
);
CREATE UNIQUE INDEX AUTHOR_INDEX ON `test_index_table01`(AUTHOR_ID);

    Output

    CREATE TABLE "public"."test_index_table01"
(
  "table01_id" INTEGER(11) NOT NULL,
  "table01_theme" VARCHAR(100) DEFAULT NULL,
  "author_name" CHAR(10) DEFAULT NULL,
  "author_id" INTEGER(11) DEFAULT NULL,
  "create_time" INTEGER DEFAULT NULL,
  PRIMARY KEY ("table01_id")
)
  WITH ( ORIENTATION = ROW, COMPRESSION = NO )
  NOCOMPRESS
  DISTRIBUTE BY HASH ("table01_id");
CREATE INDEX "author_index" ON "public"."test_index_table01" ("author_id");
Parent topic: MySQL Syntax Migration