Help Center/ GaussDB(DWS)/ Tool Guide/ DSC/ MySQL Syntax Migrating/ Indexes/ Hash Indexes
Updated on 2024-07-19 GMT+08:00
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Hash Indexes

GaussDB(DWS) does not support hash indexes. DSC will replace these indexes with normal indexes based on GaussDB(DWS) features.

  1. Inline hash indexes

    Input

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    CREATE TABLE `public`.`test_create_table03` (
	`DEMAND_ID` INT(11) NOT NULL AUTO_INCREMENT,
	`DEMAND_NAME` CHAR(100) NOT NULL,
	`THEME` VARCHAR(200) NULL DEFAULT NULL,
	`SEND_ID` INT(11) NULL DEFAULT NULL,
	`SEND_NAME` CHAR(20) NULL DEFAULT NULL,
	`SEND_TIME` DATETIME NULL DEFAULT NULL,
	`DEMAND_CONTENT` TEXT NOT NULL,
	PRIMARY KEY(`DEMAND_ID`),
    INDEX CON_INDEX(DEMAND_CONTENT(100)) USING HASH ,
    INDEX SEND_INFO_INDEX USING HASH (SEND_ID,SEND_NAME(10),SEND_TIME)
);

    Output

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    CREATE TABLE "public"."test_create_table03"
(
  "demand_id" SERIAL NOT NULL,
  "demand_name" CHAR(400) NOT NULL,
  "theme" VARCHAR(800) DEFAULT NULL,
  "send_id" INTEGER DEFAULT NULL,
  "send_name" CHAR(80) DEFAULT NULL,
  "send_time" TIMESTAMP WITHOUT TIME ZONE DEFAULT NULL,
  "demand_content" TEXT NOT NULL,
  PRIMARY KEY ("demand_id")
)
  WITH ( ORIENTATION = ROW, COMPRESSION = NO )
  NOCOMPRESS
  DISTRIBUTE BY HASH ("demand_id");
CREATE INDEX "con_index" ON "public"."test_create_table03" ("demand_content");
CREATE INDEX "send_info_index" ON "public"."test_create_table03" ("send_id","send_name","send_time");
  2. Hash index created by ALTER TABLE

    Input

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    CREATE TABLE IF NOT EXISTS `public`.`runoob_alter_test`(
    `dataType1` int NOT NULL AUTO_INCREMENT,
    `dataType2` FLOAT(10,2),
    PRIMARY KEY(`dataType1`)
)ENGINE=InnoDB DEFAULT CHARSET=utf8;

ALTER TABLE runoob_alter_test ADD KEY alterTable_addKey_indexType(dataType1) USING HASH;

    Output

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    CREATE TABLE IF NOT EXISTS "public"."runoob_alter_test"
(
  "datatype1" SERIAL NOT NULL,
  "datatype2" REAL,
  PRIMARY KEY ("datatype1")
)
  WITH ( ORIENTATION = ROW, COMPRESSION = NO )
  NOCOMPRESS
  DISTRIBUTE BY HASH ("datatype1");

CREATE INDEX "altertable_addkey_indextype" ON "public"."runoob_alter_test" ("datatype1");
  3. Hash index created by CREATE INDEX

    Input

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    CREATE TABLE `public`.`test_index_table06` (
	`ID` INT(11) NOT NULL AUTO_INCREMENT,
	`FNAME` VARCHAR(30) NOT NULL,
	`INAME` VARCHAR(30) NOT NULL,
	PRIMARY KEY (`ID`)
);
CREATE INDEX FNAME_INDEX ON TEST_INDEX_TABLE06(FNAME(10)) USING HASH;
CREATE INDEX NAME_01 ON TEST_INDEX_TABLE06(FNAME(10),INAME(10)) USING HASH;

    Output

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    CREATE TABLE "public"."test_index_table06"
(
  "id" SERIAL NOT NULL,
  "fname" VARCHAR(120) NOT NULL,
  "iname" VARCHAR(120) NOT NULL,
  PRIMARY KEY ("id")
)
  WITH ( ORIENTATION = ROW, COMPRESSION = NO )
  NOCOMPRESS
  DISTRIBUTE BY HASH ("id");
CREATE INDEX "fname_index" ON "public"."test_index_table06" ("fname");
CREATE INDEX "name_01" ON "public"."test_index_table06" ("fname","iname");
Parent topic: Indexes