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Add a check to prevent unnecessary where-clauses in index creating queries on not null columns (#617)
* Update SQL queries * Add docs * Add new check
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‎README.md

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@@ -78,6 +78,7 @@ All checks can be divided into 2 groups:
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| 28 | Columns whose names do not follow naming convention | static | yes | [sql](https://github.com/mfvanek/pg-index-health-sql/blob/master/sql/columns_not_following_naming_convention.sql) |
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| 29 | Primary keys with varchar columns instead of uuids | static | yes | [sql](https://github.com/mfvanek/pg-index-health-sql/blob/master/sql/primary_keys_with_varchar.sql) |
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| 30 | Columns with [varchar(n)](https://www.postgresql.org/docs/current/datatype-character.html) type | static | yes | [sql](https://github.com/mfvanek/pg-index-health-sql/blob/master/sql/columns_with_fixed_length_varchar.sql) |
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| 31 | Indexes with unnecessary where-clause on not null column | static | yes | [sql](https://github.com/mfvanek/pg-index-health-sql/blob/master/sql/indexes_with_unnecessary_where_clause.sql) |
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For raw sql queries see [pg-index-health-sql](https://github.com/mfvanek/pg-index-health-sql) project.
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‎doc/rus/indexes_with_unnecessary_where_clause.md

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# Проверка наличия индексов, которые имеют избыточный предикат с предложением where
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Эта проверка тесно связана с проверкой [indexes_with_null_values](indexes_with_null_values.md).
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Бывает, что разработчики начинают копировать и редактировать запросы на создание индексов.
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Это приводит к появлению запросов с предикатами вида `where <column> is not null` даже на тех столбцах,
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которые изначально имеют характеристику `not null`.
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Такие индексы:
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- содержат избыточный предикат, который вычисляется каждый раз;
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- не могут быть использованы в качестве основы для внешнего ключа, если создаются с ключевым словом `unique`.
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## SQL запрос
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- [indexes_with_unnecessary_where_clause.sql](https://github.com/mfvanek/pg-index-health-sql/blob/master/sql/indexes_with_unnecessary_where_clause.sql)
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## Тип проверки
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- **static** (может выполняться на пустой БД в компонентных\интеграционных тестах)
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## Поддержка секционированных таблиц
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Поддерживает секционированные таблицы.
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Проверка выполняется на самой секционированной таблице (родительской). Отдельные секции (потомки) игнорируются.
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## Скрипт для воспроизведения
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```sql
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create schema if not exists demo;
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create table if not exists demo.t1(
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id bigint not null primary key,
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id_ref bigint not null);
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create index if not exists idx_t1_id_ref on demo.t1 (id_ref) where id_ref is not null;
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create table if not exists demo.t2(
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"first-ref" bigint not null,
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second_ref bigint not null,
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t1_id bigint references demo.t1 (id));
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create index if not exists "idx_t2_first-ref_second_ref" on demo.t2 (second_ref, "first-ref") where "first-ref" is not null;
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create index if not exists idx_t2_id_ref on demo.t2 (t1_id) where t1_id is not null;
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create index if not exists idx_second_ref_t1_id on demo.t2 (t1_id, second_ref) where t1_id is not null;
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create table if not exists demo.one_partitioned(
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"first-ref" bigint not null,
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second_ref bigint not null
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) partition by range (second_ref);
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create index if not exists "idx_second_ref_first-ref" on demo.one_partitioned (second_ref, "first-ref") where "first-ref" is not null;
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create table if not exists demo.one_default partition of demo.one_partitioned default;
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```

‎doc/rus/primary_keys_with_varchar.md

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select id_long from demo.t_varchar_long;
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create table if not exists demo.t_link (
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id_long varchar(36) not null references demo.t_varchar_long (id_long),
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"id-short" varchar(32) not null references demo."t-varchar-short" ("id-short"),
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id_long varchar(36) not null references demo.t_varchar_long (id_long),
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primary key (id_long, "id-short")
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);
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‎pg-index-health-core/src/main/java/io/github/mfvanek/pg/core/checks/common/Diagnostic.java

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@@ -53,7 +53,8 @@ public enum Diagnostic implements CheckTypeAware {
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OBJECTS_NOT_FOLLOWING_NAMING_CONVENTION("objects_not_following_naming_convention.sql"),
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COLUMNS_NOT_FOLLOWING_NAMING_CONVENTION("columns_not_following_naming_convention.sql"),
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PRIMARY_KEYS_WITH_VARCHAR("primary_keys_with_varchar.sql"),
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COLUMNS_WITH_FIXED_LENGTH_VARCHAR("columns_with_fixed_length_varchar.sql");
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COLUMNS_WITH_FIXED_LENGTH_VARCHAR("columns_with_fixed_length_varchar.sql"),
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INDEXES_WITH_UNNECESSARY_WHERE_CLAUSE("indexes_with_unnecessary_where_clause.sql");
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private final ExecutionTopology executionTopology;
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private final String sqlQueryFileName;

‎pg-index-health-core/src/main/java/io/github/mfvanek/pg/core/checks/host/IndexesWithUnnecessaryWhereClauseCheckOnHost.java

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/*
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* Copyright (c) 2019-2025. Ivan Vakhrushev and others.
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* https://github.com/mfvanek/pg-index-health
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*
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* This file is a part of "pg-index-health" - a Java library for
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* analyzing and maintaining indexes health in PostgreSQL databases.
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*
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* Licensed under the Apache License 2.0
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*/
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package io.github.mfvanek.pg.core.checks.host;
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import io.github.mfvanek.pg.connection.PgConnection;
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import io.github.mfvanek.pg.core.checks.common.Diagnostic;
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import io.github.mfvanek.pg.core.checks.extractors.IndexWithColumnsExtractor;
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import io.github.mfvanek.pg.model.context.PgContext;
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import io.github.mfvanek.pg.model.index.IndexWithColumns;
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import java.util.List;
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import javax.annotation.Nonnull;
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/**
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* Check for indexes with unnecessary where-clause on not null column on a specific host.
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*
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* @author Ivan Vakhrushev
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* @since 0.14.6
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*/
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public class IndexesWithUnnecessaryWhereClauseCheckOnHost extends AbstractCheckOnHost<IndexWithColumns> {
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public IndexesWithUnnecessaryWhereClauseCheckOnHost(@Nonnull final PgConnection pgConnection) {
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super(IndexWithColumns.class, pgConnection, Diagnostic.INDEXES_WITH_UNNECESSARY_WHERE_CLAUSE);
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}
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/**
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* Returns indexes with unnecessary where-clause on not null column in the specified schema.
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*
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* @param pgContext check's context with the specified schema
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* @return list of indexes with unnecessary where-clause on not null column
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*/
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@Nonnull
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@Override
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protected List<IndexWithColumns> doCheck(@Nonnull final PgContext pgContext) {
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return executeQuery(pgContext, IndexWithColumnsExtractor.of());
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}
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}

‎pg-index-health-core/src/main/resources

‎pg-index-health-core/src/test/java/io/github/mfvanek/pg/core/checks/host/IndexesWithUnnecessaryWhereClauseCheckOnHostTest.java

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/*
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* Copyright (c) 2019-2025. Ivan Vakhrushev and others.
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* https://github.com/mfvanek/pg-index-health
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*
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* This file is a part of "pg-index-health" - a Java library for
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* analyzing and maintaining indexes health in PostgreSQL databases.
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*
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* Licensed under the Apache License 2.0
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*/
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package io.github.mfvanek.pg.core.checks.host;
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import io.github.mfvanek.pg.core.checks.common.DatabaseCheckOnHost;
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import io.github.mfvanek.pg.core.checks.common.Diagnostic;
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import io.github.mfvanek.pg.core.fixtures.support.DatabaseAwareTestBase;
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import io.github.mfvanek.pg.core.fixtures.support.DatabasePopulator;
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import io.github.mfvanek.pg.model.column.Column;
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import io.github.mfvanek.pg.model.context.PgContext;
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import io.github.mfvanek.pg.model.index.IndexWithColumns;
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import io.github.mfvanek.pg.model.predicates.SkipTablesByNamePredicate;
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import org.junit.jupiter.api.Test;
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import org.junit.jupiter.params.ParameterizedTest;
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import org.junit.jupiter.params.provider.ValueSource;
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import java.util.List;
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import static io.github.mfvanek.pg.core.support.AbstractCheckOnHostAssert.assertThat;
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class IndexesWithUnnecessaryWhereClauseCheckOnHostTest extends DatabaseAwareTestBase {
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private final DatabaseCheckOnHost<IndexWithColumns> check = new IndexesWithUnnecessaryWhereClauseCheckOnHost(getPgConnection());
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@Test
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void shouldSatisfyContract() {
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assertThat(check)
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.hasType(IndexWithColumns.class)
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.hasDiagnostic(Diagnostic.INDEXES_WITH_UNNECESSARY_WHERE_CLAUSE)
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.hasHost(getHost())
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.isStatic();
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}
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@ParameterizedTest
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@ValueSource(strings = {PgContext.DEFAULT_SCHEMA_NAME, "custom"})
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void onDatabaseWithThem(final String schemaName) {
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executeTestOnDatabase(schemaName, DatabasePopulator::withUnnecessaryWhereClause, ctx -> {
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assertThat(check)
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.executing(ctx)
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.hasSize(2)
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.containsExactly(
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IndexWithColumns.ofSingle(ctx, "t1", "idx_t1_id_ref", 0L, Column.ofNotNull(ctx, "t1", "id_ref")),
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IndexWithColumns.ofColumns(ctx, "t2", "\"idx_t2_first-ref_second_ref\"", 0L, List.of(
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Column.ofNotNull(ctx, "t2", "second_ref"), Column.ofNotNull(ctx, "t2", "\"first-ref\"")))
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);
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assertThat(check)
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.executing(ctx, SkipTablesByNamePredicate.of(ctx, List.of("t1", "t2")))
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.isEmpty();
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});
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}
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@ParameterizedTest
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@ValueSource(strings = {PgContext.DEFAULT_SCHEMA_NAME, "custom"})
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void shouldWorkWithPartitionedTables(final String schemaName) {
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executeTestOnDatabase(schemaName, DatabasePopulator::withUnnecessaryWhereClauseInPartitionedIndex, ctx ->
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assertThat(check)
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.executing(ctx)
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.hasSize(1)
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.containsExactly(
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IndexWithColumns.ofColumns(ctx, "one_partitioned", "\"idx_second_ref_first-ref\"", 0L, List.of(
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Column.ofNotNull(ctx, "one_partitioned", "second_ref"), Column.ofNotNull(ctx, "one_partitioned", "\"first-ref\"")))
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)
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);
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}
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}

‎pg-index-health-core/src/testFixtures/java/io/github/mfvanek/pg/core/fixtures/support/DatabasePopulator.java

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import io.github.mfvanek.pg.core.fixtures.support.statements.CreateFunctionsStatement;
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import io.github.mfvanek.pg.core.fixtures.support.statements.CreateIndexWithBooleanValuesStatement;
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import io.github.mfvanek.pg.core.fixtures.support.statements.CreateIndexWithNullValuesStatement;
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import io.github.mfvanek.pg.core.fixtures.support.statements.CreateIndexWithUnnecessaryWhereClauseStatement;
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import io.github.mfvanek.pg.core.fixtures.support.statements.CreateIndexesOnArrayColumnStatement;
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import io.github.mfvanek.pg.core.fixtures.support.statements.CreateIndexesWithDifferentOpclassStatement;
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import io.github.mfvanek.pg.core.fixtures.support.statements.CreateMaterializedViewStatement;
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import io.github.mfvanek.pg.core.fixtures.support.statements.CreateNotSuitableIndexForForeignKeyStatement;
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import io.github.mfvanek.pg.core.fixtures.support.statements.CreatePartitionedIndexWithUnnecessaryWhereClauseStatement;
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import io.github.mfvanek.pg.core.fixtures.support.statements.CreatePartitionedTableWithDroppedColumnStatement;
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import io.github.mfvanek.pg.core.fixtures.support.statements.CreatePartitionedTableWithJsonAndSerialColumnsStatement;
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import io.github.mfvanek.pg.core.fixtures.support.statements.CreatePartitionedTableWithNullableFieldsStatement;
@@ -371,6 +373,11 @@ public DatabasePopulator withVarcharInPartitionedTable() {
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return register(124, new CreatePartitionedTableWithVarcharStatement());
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}
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@Nonnull
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public DatabasePopulator withUnnecessaryWhereClauseInPartitionedIndex() {
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return register(125, new CreatePartitionedIndexWithUnnecessaryWhereClauseStatement());
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}
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@Nonnull
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public DatabasePopulator withEmptyTable() {
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return register(130, new CreateEmptyTableStatement());
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return register(137, new DropColumnStatement("accounts", "account_number"));
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}
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@Nonnull
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public DatabasePopulator withUnnecessaryWhereClause() {
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return register(138, new CreateIndexWithUnnecessaryWhereClauseStatement());
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}
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public void populate() {
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try (SchemaNameHolder ignored = SchemaNameHolder.with(schemaName)) {
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ExecuteUtils.executeInTransaction(dataSource, statementsToExecuteInSameTransaction.values());

‎pg-index-health-core/src/testFixtures/java/io/github/mfvanek/pg/core/fixtures/support/statements/CreateIndexWithUnnecessaryWhereClauseStatement.java

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/*
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* Copyright (c) 2019-2025. Ivan Vakhrushev and others.
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* https://github.com/mfvanek/pg-index-health
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*
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* This file is a part of "pg-index-health" - a Java library for
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* analyzing and maintaining indexes health in PostgreSQL databases.
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*
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* Licensed under the Apache License 2.0
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*/
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package io.github.mfvanek.pg.core.fixtures.support.statements;
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import java.util.List;
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import javax.annotation.Nonnull;
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public class CreateIndexWithUnnecessaryWhereClauseStatement extends AbstractDbStatement {
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@Nonnull
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@Override
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protected List<String> getSqlToExecute() {
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return List.of(
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"create table if not exists {schemaName}.t1(" +
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"id bigint not null primary key," +
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"id_ref bigint not null);",
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"create index if not exists idx_t1_id_ref on {schemaName}.t1 (id_ref) " +
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"where id_ref is not null;",
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"create table if not exists {schemaName}.t2(" +
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"\"first-ref\" bigint not null," +
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"second_ref bigint not null," +
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"t1_id bigint references {schemaName}.t1 (id));",
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"create index if not exists \"idx_t2_first-ref_second_ref\" on {schemaName}.t2 (second_ref, \"first-ref\") " +
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"where \"first-ref\" is not null;",
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"create index if not exists idx_t2_id_ref on {schemaName}.t2 (t1_id) " +
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"where t1_id is not null;",
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"create index if not exists idx_second_ref_t1_id on {schemaName}.t2 (t1_id, second_ref) " +
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"where t1_id is not null;"
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);
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}
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}

‎pg-index-health-core/src/testFixtures/java/io/github/mfvanek/pg/core/fixtures/support/statements/CreatePartitionedIndexWithUnnecessaryWhereClauseStatement.java

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/*
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* Copyright (c) 2019-2025. Ivan Vakhrushev and others.
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* https://github.com/mfvanek/pg-index-health
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*
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* This file is a part of "pg-index-health" - a Java library for
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* analyzing and maintaining indexes health in PostgreSQL databases.
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*
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* Licensed under the Apache License 2.0
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*/
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package io.github.mfvanek.pg.core.fixtures.support.statements;
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import java.util.List;
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import javax.annotation.Nonnull;
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public class CreatePartitionedIndexWithUnnecessaryWhereClauseStatement extends AbstractDbStatement {
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@Nonnull
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@Override
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protected List<String> getSqlToExecute() {
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return List.of(
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"create table if not exists {schemaName}.one_partitioned(" +
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"\"first-ref\" bigint not null," +
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"second_ref bigint not null" +
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") partition by range (second_ref);",
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"create index if not exists \"idx_second_ref_first-ref\" on {schemaName}.one_partitioned (second_ref, \"first-ref\") " +
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"where \"first-ref\" is not null;",
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"create table if not exists {schemaName}.one_default partition of {schemaName}.one_partitioned default;"
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);
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}
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}

‎pg-index-health-core/src/testFixtures/java/io/github/mfvanek/pg/core/fixtures/support/statements/CreateTableWithFixedLengthVarcharStatement.java

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"id_long varchar(36) not null primary key);",
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"insert into {schemaName}.t_varchar_long values (gen_random_uuid());",
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"create table if not exists {schemaName}.t_link (" +
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"id_long varchar(36) not null references {schemaName}.t_varchar_long (id_long)," +
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"\"id-short\" varchar(32) not null references {schemaName}.\"t-varchar-short\" (\"id-short\")," +
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"id_long varchar(36) not null references {schemaName}.t_varchar_long (id_long)," +
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"primary key (id_long, \"id-short\"));",
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"create table if not exists {schemaName}.t_varchar_long_not_pk (" +
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"id_long varchar(36) not null);",

‎pg-index-health-logger/src/main/java/io/github/mfvanek/pg/health/logger/DatabaseChecksOnCluster.java

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import io.github.mfvanek.pg.health.checks.cluster.IndexesWithBloatCheckOnCluster;
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import io.github.mfvanek.pg.health.checks.cluster.IndexesWithBooleanCheckOnCluster;
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import io.github.mfvanek.pg.health.checks.cluster.IndexesWithNullValuesCheckOnCluster;
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import io.github.mfvanek.pg.health.checks.cluster.IndexesWithUnnecessaryWhereClauseCheckOnCluster;
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import io.github.mfvanek.pg.health.checks.cluster.IntersectedForeignKeysCheckOnCluster;
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import io.github.mfvanek.pg.health.checks.cluster.IntersectedIndexesCheckOnCluster;
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import io.github.mfvanek.pg.health.checks.cluster.InvalidIndexesCheckOnCluster;
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new ObjectsNotFollowingNamingConventionCheckOnCluster(haPgConnection),
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new ColumnsNotFollowingNamingConventionCheckOnCluster(haPgConnection),
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new PrimaryKeysWithVarcharCheckOnCluster(haPgConnection),
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new ColumnsWithFixedLengthVarcharCheckOnCluster(haPgConnection)
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new ColumnsWithFixedLengthVarcharCheckOnCluster(haPgConnection),
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new IndexesWithUnnecessaryWhereClauseCheckOnCluster(haPgConnection)
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);
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}
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