Attempt to define a second primary key with IF NOT EXISTS - h2

Question

Why is this statement failing despite the "IF NOT EXISTS" clause?
org.h2.jdbc.JdbcSQLSyntaxErrorException: Attempt to define a second primary key; SQL statement:
ALTER TABLE QRTZ_CALENDARS
ADD CONSTRAINT IF NOT EXISTS PK_QRTZ_CALENDARS PRIMARY KEY ( SCHED_NAME, CALENDAR_NAME ) [90017-212]
H2 is run in memory mode jdbc:h2:mem:quartz;INIT=RUNSCRIPT FROM 'classpath:tables_h2.sql'
CREATE TABLE IF NOT EXISTS QRTZ_CALENDARS (
SCHED_NAME VARCHAR(120) NOT NULL,
CALENDAR_NAME VARCHAR (200) NOT NULL ,
CALENDAR IMAGE NOT NULL
);
If I move the PK definition into table definition the error goes away.
The script is
CREATE TABLE IF NOT EXISTS QRTZ_CALENDARS (
SCHED_NAME VARCHAR(120) NOT NULL,
CALENDAR_NAME VARCHAR (200) NOT NULL ,
CALENDAR IMAGE NOT NULL
);
CREATE TABLE IF NOT EXISTS QRTZ_CRON_TRIGGERS (
SCHED_NAME VARCHAR(120) NOT NULL,
TRIGGER_NAME VARCHAR (200) NOT NULL ,
TRIGGER_GROUP VARCHAR (200) NOT NULL ,
CRON_EXPRESSION VARCHAR (120) NOT NULL ,
TIME_ZONE_ID VARCHAR (80)
);
CREATE TABLE IF NOT EXISTS QRTZ_FIRED_TRIGGERS (
SCHED_NAME VARCHAR(120) NOT NULL,
ENTRY_ID VARCHAR (95) NOT NULL ,
TRIGGER_NAME VARCHAR (200) NOT NULL ,
TRIGGER_GROUP VARCHAR (200) NOT NULL ,
INSTANCE_NAME VARCHAR (200) NOT NULL ,
FIRED_TIME BIGINT NOT NULL ,
SCHED_TIME BIGINT NOT NULL ,
PRIORITY INTEGER NOT NULL ,
STATE VARCHAR (16) NOT NULL,
JOB_NAME VARCHAR (200) NULL ,
JOB_GROUP VARCHAR (200) NULL ,
IS_NONCONCURRENT BOOLEAN NULL ,
REQUESTS_RECOVERY BOOLEAN NULL
);
CREATE TABLE IF NOT EXISTS QRTZ_PAUSED_TRIGGER_GRPS (
SCHED_NAME VARCHAR(120) NOT NULL,
TRIGGER_GROUP VARCHAR (200) NOT NULL
);
CREATE TABLE IF NOT EXISTS QRTZ_SCHEDULER_STATE (
SCHED_NAME VARCHAR(120) NOT NULL,
INSTANCE_NAME VARCHAR (200) NOT NULL ,
LAST_CHECKIN_TIME BIGINT NOT NULL ,
CHECKIN_INTERVAL BIGINT NOT NULL
);
CREATE TABLE IF NOT EXISTS QRTZ_LOCKS (
SCHED_NAME VARCHAR(120) NOT NULL,
LOCK_NAME VARCHAR (40) NOT NULL
);
CREATE TABLE IF NOT EXISTS QRTZ_JOB_DETAILS (
SCHED_NAME VARCHAR(120) NOT NULL,
JOB_NAME VARCHAR (200) NOT NULL ,
JOB_GROUP VARCHAR (200) NOT NULL ,
DESCRIPTION VARCHAR (250) NULL ,
JOB_CLASS_NAME VARCHAR (250) NOT NULL ,
IS_DURABLE BOOLEAN NOT NULL ,
IS_NONCONCURRENT BOOLEAN NOT NULL ,
IS_UPDATE_DATA BOOLEAN NOT NULL ,
REQUESTS_RECOVERY BOOLEAN NOT NULL ,
JOB_DATA IMAGE NULL
);
CREATE TABLE IF NOT EXISTS QRTZ_SIMPLE_TRIGGERS (
SCHED_NAME VARCHAR(120) NOT NULL,
TRIGGER_NAME VARCHAR (200) NOT NULL ,
TRIGGER_GROUP VARCHAR (200) NOT NULL ,
REPEAT_COUNT BIGINT NOT NULL ,
REPEAT_INTERVAL BIGINT NOT NULL ,
TIMES_TRIGGERED BIGINT NOT NULL
);
CREATE TABLE IF NOT EXISTS QRTZ_SIMPROP_TRIGGERS (
SCHED_NAME VARCHAR(120) NOT NULL,
TRIGGER_NAME VARCHAR(200) NOT NULL,
TRIGGER_GROUP VARCHAR(200) NOT NULL,
STR_PROP_1 VARCHAR(512) NULL,
STR_PROP_2 VARCHAR(512) NULL,
STR_PROP_3 VARCHAR(512) NULL,
INT_PROP_1 INTEGER NULL,
INT_PROP_2 INTEGER NULL,
LONG_PROP_1 BIGINT NULL,
LONG_PROP_2 BIGINT NULL,
DEC_PROP_1 NUMERIC(13,4) NULL,
DEC_PROP_2 NUMERIC(13,4) NULL,
BOOL_PROP_1 BOOLEAN NULL,
BOOL_PROP_2 BOOLEAN NULL
);
CREATE TABLE IF NOT EXISTS QRTZ_BLOB_TRIGGERS (
SCHED_NAME VARCHAR(120) NOT NULL,
TRIGGER_NAME VARCHAR (200) NOT NULL ,
TRIGGER_GROUP VARCHAR (200) NOT NULL ,
BLOB_DATA IMAGE NULL
);
CREATE TABLE IF NOT EXISTS QRTZ_TRIGGERS (
SCHED_NAME VARCHAR(120) NOT NULL,
TRIGGER_NAME VARCHAR (200) NOT NULL ,
TRIGGER_GROUP VARCHAR (200) NOT NULL ,
JOB_NAME VARCHAR (200) NOT NULL ,
JOB_GROUP VARCHAR (200) NOT NULL ,
DESCRIPTION VARCHAR (250) NULL ,
NEXT_FIRE_TIME BIGINT NULL ,
PREV_FIRE_TIME BIGINT NULL ,
PRIORITY INTEGER NULL ,
TRIGGER_STATE VARCHAR (16) NOT NULL ,
TRIGGER_TYPE VARCHAR (8) NOT NULL ,
START_TIME BIGINT NOT NULL ,
END_TIME BIGINT NULL ,
CALENDAR_NAME VARCHAR (200) NULL ,
MISFIRE_INSTR SMALLINT NULL ,
JOB_DATA IMAGE NULL
);
ALTER TABLE QRTZ_CALENDARS ADD
CONSTRAINT IF NOT EXISTS PK_QRTZ_CALENDARS PRIMARY KEY
(
SCHED_NAME,
CALENDAR_NAME
);
ALTER TABLE QRTZ_CRON_TRIGGERS ADD
CONSTRAINT IF NOT EXISTS PK_QRTZ_CRON_TRIGGERS PRIMARY KEY
(
SCHED_NAME,
TRIGGER_NAME,
TRIGGER_GROUP
);
ALTER TABLE QRTZ_FIRED_TRIGGERS ADD
CONSTRAINT IF NOT EXISTS PK_QRTZ_FIRED_TRIGGERS PRIMARY KEY
(
SCHED_NAME,
ENTRY_ID
);
ALTER TABLE QRTZ_PAUSED_TRIGGER_GRPS ADD
CONSTRAINT IF NOT EXISTS PK_QRTZ_PAUSED_TRIGGER_GRPS PRIMARY KEY
(
SCHED_NAME,
TRIGGER_GROUP
);
ALTER TABLE QRTZ_SCHEDULER_STATE ADD
CONSTRAINT IF NOT EXISTS PK_QRTZ_SCHEDULER_STATE PRIMARY KEY
(
SCHED_NAME,
INSTANCE_NAME
);
ALTER TABLE QRTZ_LOCKS ADD
CONSTRAINT IF NOT EXISTS PK_QRTZ_LOCKS PRIMARY KEY
(
SCHED_NAME,
LOCK_NAME
);
ALTER TABLE QRTZ_JOB_DETAILS ADD
CONSTRAINT IF NOT EXISTS PK_QRTZ_JOB_DETAILS PRIMARY KEY
(
SCHED_NAME,
JOB_NAME,
JOB_GROUP
);
ALTER TABLE QRTZ_SIMPLE_TRIGGERS ADD
CONSTRAINT IF NOT EXISTS PK_QRTZ_SIMPLE_TRIGGERS PRIMARY KEY
(
SCHED_NAME,
TRIGGER_NAME,
TRIGGER_GROUP
);
ALTER TABLE QRTZ_SIMPROP_TRIGGERS ADD
CONSTRAINT IF NOT EXISTS PK_QRTZ_SIMPROP_TRIGGERS PRIMARY KEY
(
SCHED_NAME,
TRIGGER_NAME,
TRIGGER_GROUP
);
ALTER TABLE QRTZ_TRIGGERS ADD
CONSTRAINT IF NOT EXISTS PK_QRTZ_TRIGGERS PRIMARY KEY
(
SCHED_NAME,
TRIGGER_NAME,
TRIGGER_GROUP
);
ALTER TABLE QRTZ_CRON_TRIGGERS ADD
CONSTRAINT IF NOT EXISTS FK_QRTZ_CRON_TRIGGERS_QRTZ_TRIGGERS FOREIGN KEY
(
SCHED_NAME,
TRIGGER_NAME,
TRIGGER_GROUP
) REFERENCES QRTZ_TRIGGERS (
SCHED_NAME,
TRIGGER_NAME,
TRIGGER_GROUP
) ON DELETE CASCADE;
ALTER TABLE QRTZ_SIMPLE_TRIGGERS ADD
CONSTRAINT IF NOT EXISTS FK_QRTZ_SIMPLE_TRIGGERS_QRTZ_TRIGGERS FOREIGN KEY
(
SCHED_NAME,
TRIGGER_NAME,
TRIGGER_GROUP
) REFERENCES QRTZ_TRIGGERS (
SCHED_NAME,
TRIGGER_NAME,
TRIGGER_GROUP
) ON DELETE CASCADE;
ALTER TABLE QRTZ_SIMPROP_TRIGGERS ADD
CONSTRAINT IF NOT EXISTS FK_QRTZ_SIMPROP_TRIGGERS_QRTZ_TRIGGERS FOREIGN KEY
(
SCHED_NAME,
TRIGGER_NAME,
TRIGGER_GROUP
) REFERENCES QRTZ_TRIGGERS (
SCHED_NAME,
TRIGGER_NAME,
TRIGGER_GROUP
) ON DELETE CASCADE;
ALTER TABLE QRTZ_TRIGGERS ADD
CONSTRAINT IF NOT EXISTS FK_QRTZ_TRIGGERS_QRTZ_JOB_DETAILS FOREIGN KEY
(
SCHED_NAME,
JOB_NAME,
JOB_GROUP
) REFERENCES QRTZ_JOB_DETAILS (
SCHED_NAME,
JOB_NAME,
JOB_GROUP
);
COMMIT;
The error only happens when concurrent connections are established.
If I set the pool size to 1 it does not occur.
If I set the pool size to 2 I see it logged once.
If I set the pool size to 3 I see it logged twice.
The error seems to be gone when the connection pool retries.
It all looks like a concurrency bug in H2

Answer 1

IF NOT EXISTS checks only presence of constraint with exactly the same name. This exception indicates that your table already has a primary key constraint with the same or other set of columns, but with different name.
If you're sure that this table either has a primary key constraint on these two columns with unknown name or doesn't have a primary key constraint at all, you can replace your command with the following one:
EXECUTE IMMEDIATE
CASE WHEN NOT EXISTS (
SELECT * FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS
WHERE TABLE_NAME = 'QRTZ_CALENDARS' AND CONSTRAINT_TYPE = 'PRIMARY KEY')
THEN 'ALTER TABLE QRTZ_CALENDARS ADD CONSTRAINT PK_QRTZ_CALENDARS PRIMARY KEY (SCHED_NAME, CALENDAR_NAME)'
ELSE ''
END;