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`foreignKeyConstraintExists` not working

See original GitHub issue

Environment

Liquibase Version:

 ./bin/liquibase --version
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##  \_____/_|\__, |\__,_|_|_.__/ \__,_|___/\___|  ##
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##  Get documentation at docs.liquibase.com       ##
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##  Free schema change activity reports at        ##
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Starting Liquibase at 17:02:20 (version 4.7.0 #1140 built at 2022-01-07 19:26+0000)
Liquibase Version: 4.7.0
Liquibase Community 4.7.0 by Liquibase
Running Java under /usr/java/jdk1.8.0_144/jre (Version 1.8.0_144)

Note: The same Liquibase changeSet worked in Liquibase Version: 3.10.2

Liquibase Integration & Version: CLI

Liquibase Extension(s) & Version:

Database Vendor & Version:

> SELECT version();
                                   version                                    
------------------------------------------------------------------------------
 PostgreSQL 10.13 on x86_64-pc-linux-gnu, compiled by gcc (GCC) 4.9.3, 64-bit

Operating System Type & Version:

$ cat /etc/os-release 
NAME="CentOS Linux"
VERSION="7 (Core)"
ID="centos"
ID_LIKE="rhel fedora"
VERSION_ID="7"
PRETTY_NAME="CentOS Linux 7 (Core)"
ANSI_COLOR="0;31"
CPE_NAME="cpe:/o:centos:centos:7"
HOME_URL="https://www.centos.org/"
BUG_REPORT_URL="https://bugs.centos.org/"

CENTOS_MANTISBT_PROJECT="CentOS-7"
CENTOS_MANTISBT_PROJECT_VERSION="7"
REDHAT_SUPPORT_PRODUCT="centos"
REDHAT_SUPPORT_PRODUCT_VERSION="7"

Description

foreignKeyConstraintExists doesn’t seem to be working. I’m trying to MARK_RAN if foreignKey already exists so I just create the FK if it is absent.

This was working with Liquibase 3.10.2. I’m in the process of upgrading it in order to improve performance as a simple migration took multiple hours with the previous version.

Steps To Reproduce

<changeSet ...>
  <preConditions onFail="MARK_RAN">
    <not>
      <foreignKeyConstraintExists foreignKeyName="FK_NAME"/>
    </not>
  </preConditions>
  <addForeignKeyConstraint constraintName="FK_NAME"  ... />
</changeSet>

Actual Behavior

changeSet execution fails trying to execute the addForeignKeyConstraint (since the constraint with that name already exists).

Expected/Desired Behavior

The precondition onFail should’ve been called (adding the changeSet as MARK_RAN to liquibase changelog), and, as such, the changeSet shouldn’t execute addForeignKeyContstraint.

Additional Context

I was able to implement a temporary workaround specific to the database vendor that confirms that the FK exists.

        <preConditions onFail="MARK_RAN">
            <sqlCheck expectedResult="0">
              SELECT COUNT(*) FROM information_schema.table_constraints WHERE constraint_name='FK_NAME' AND table_schema = '<x>'
            </sqlCheck>
        </preConditions>

From my (limited) understanding, Liquibase does some sort of DB snapshot, which it uses to verify some of these pre-conditions (not the sqlCheck) and it doesn’t seem to be importing the ForeignKey to that snapshot.