vacuum_count 和 analyze_count 在 VACUUM ANALYZE 之后都为零
Both vacuum_count and analyze_count are zero after VACUUM ANALYZE
我编写了一个单元测试，它修改了 table（INSERT 和 DELETE），然后手动修改 VACUUM 和 ANALYZE 是它，然后我查询 pg_stat_user_tables 以确保 VACUUM 和 ANALYZE 确实有一些效果。
我使用以下 SQL：
select
tbl.relid,
tbl.schemaname,
tbl.n_tup_del,
tbl.n_live_tup,
tbl.n_dead_tup,
tbl.n_mod_since_analyze,
tbl.vacuum_count,
tbl.analyze_count
from
pg_stat_user_tables tbl
where
tbl.relname = lower('...')
and schemaname = current_schema();
对于常规 tables 和
select
tbl.relid,
tbl.schemaname,
tbl.n_tup_del,
tbl.n_live_tup,
tbl.n_dead_tup,
tbl.n_mod_since_analyze,
tbl.vacuum_count,
tbl.analyze_count
from
pg_stat_user_tables tbl
join
pg_namespace nsp
on
tbl.schemaname = nsp.nspname
where
tbl.relname = lower('...')
and nsp.oid = pg_my_temp_schema();
对于临时的。
仍然，当我 运行 我的例子时，我观察到 vacuum_count 和 analyze_count 都是零，并且 table 包含很多死元组，例如：
relid = 913896
schemaname = pg_temp_20
n_tup_del = 10000
n_live_tup = 10000
n_dead_tup = 10000
n_mod_since_analyze = 30000
vacuum_count = 0
analyze_count = 0
这是为什么？
自带的代码示例如下：
package com.example;
import static com.example.AutoCommitMode.COMMIT;
import static com.example.AutoCommitMode.ON;
import static com.example.AutoCommitMode.ROLLBACK;
import static java.lang.String.format;
import static java.util.Arrays.asList;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.List;
import javax.sql.DataSource;
import org.eclipse.jdt.annotation.NonNull;
import org.eclipse.jdt.annotation.Nullable;
import org.postgresql.ds.PGSimpleDataSource;
import org.postgresql.ds.common.BaseDataSource;
import org.testng.Assert;
import org.testng.annotations.DataProvider;
import org.testng.annotations.Test;
public final class PostgreSqlVacuumTest {
private static final String JDBC_URL = "jdbc:postgresql://localhost:5432/postgres?currentSchema=sandbox";
@DataProvider
private static @Nullable Object @NonNull[]@NonNull[] getParameters() {
@NonNull final List<@Nullable Object @NonNull[]> parameters = new ArrayList<>();
parameters.add(new @Nullable Object[] {"A", false, ON});
parameters.add(new @Nullable Object[] {"B", false, COMMIT});
parameters.add(new @Nullable Object[] {"C", false, ROLLBACK});
parameters.add(new @Nullable Object[] {"D", true, ON});
parameters.add(new @Nullable Object[] {"E", true, COMMIT});
parameters.add(new @Nullable Object[] {"F", true, ROLLBACK});
return parameters.toArray(new @Nullable Object @NonNull[0]@NonNull[]);
}
@Test(dataProvider = "getParameters")
@SuppressWarnings({"static-method", "incomplete-switch"})
public void test(@NonNull final String tableName,
final boolean temporary,
final AutoCommitMode mode)
throws SQLException {
final DataSource dataSource = new PGSimpleDataSource();
((BaseDataSource) dataSource).setUrl(JDBC_URL);
try (final Connection conn = dataSource.getConnection("user", "password")) {
try (final Statement stmt = conn.createStatement()) {
try {
stmt.executeUpdate(format("drop table %s", tableName));
} catch (@SuppressWarnings("unused") final SQLException ignored) {
// ignore
}
stmt.executeUpdate(format("create %stable %s (id bigint not null)",
temporary ? "temporary " : "",
tableName));
conn.setAutoCommit(mode.autoCommit);
for (int i = 0; i < 10000; i++) {
stmt.executeUpdate(format("insert into %s (id) values (%d)", tableName, i));
}
stmt.executeUpdate(format("delete from %s", tableName));
for (int i = 0; i < 10000; i++) {
stmt.executeUpdate(format("insert into %s (id) values (%d)", tableName, i));
}
switch (mode) {
case COMMIT:
conn.commit();
break;
case ROLLBACK:
conn.rollback();
break;
}
try (final ResultSet countHolder = stmt.executeQuery(format("select count(*) from %s", tableName))) {
Assert.assertTrue(countHolder.next());
final long count = countHolder.getLong(1);
Assert.assertEquals(count, mode == ROLLBACK ? 0L : 10000L);
Assert.assertFalse(countHolder.next());
}
switch (mode) {
case ON:
stmt.executeUpdate(format("vacuum analyze %s", tableName));
break;
case COMMIT:
case ROLLBACK:
// VACUUM cannot be executed inside a transaction block.
conn.setAutoCommit(true);
try {
stmt.executeUpdate(format("vacuum analyze %s", tableName));
} finally {
conn.setAutoCommit(false);
}
break;
}
diagnose(tableName, temporary, stmt);
}
}
}
private static void diagnose(@NonNull final String tableName,
final boolean temporary,
@NonNull final Statement stmt)
throws SQLException {
final List<String> columns = asList("relid", "schemaname", "n_tup_del", "n_live_tup", "n_dead_tup", "n_mod_since_analyze", "vacuum_count", "analyze_count");
final String diagSql = temporary
? "select\n" +
" tbl.relid,\n" +
" tbl.schemaname,\n" +
" tbl.n_tup_del,\n" +
" tbl.n_live_tup,\n" +
" tbl.n_dead_tup,\n" +
" tbl.n_mod_since_analyze,\n" +
" tbl.vacuum_count,\n" +
" tbl.analyze_count\n" +
"from\n" +
" pg_stat_user_tables tbl\n" +
"join\n" +
" pg_namespace nsp\n" +
"on\n" +
" tbl.schemaname = nsp.nspname\n" +
"where\n" +
" tbl.relname = lower('%s')\n" +
" and nsp.oid = pg_my_temp_schema()"
: "select\n" +
" tbl.relid,\n" +
" tbl.schemaname,\n" +
" tbl.n_tup_del,\n" +
" tbl.n_live_tup,\n" +
" tbl.n_dead_tup,\n" +
" tbl.n_mod_since_analyze,\n" +
" tbl.vacuum_count,\n" +
" tbl.analyze_count\n" +
"from\n" +
" pg_stat_user_tables tbl\n" +
"where\n" +
" tbl.relname = lower('%s')\n" +
" and schemaname = current_schema()";
try (final ResultSet rset = stmt.executeQuery(format(diagSql, tableName))) {
while (rset.next()) {
System.out.println("---------------");
for (final String column : columns) {
System.out.println("\t" + column + " = " + rset.getObject(column));
}
}
}
}
}
enum AutoCommitMode {
ON(true),
COMMIT(false),
ROLLBACK(false),
;
final boolean autoCommit;
AutoCommitMode(final boolean autoCommit) {
this.autoCommit = autoCommit;
}
}
您确定用户（您用来手动 运行 VACUUM 的用户）具有足够的权限吗？
文档说：
"VACUUM processes every table in the current database that the current user has permission to vacuum"
VACUUM（没有 FULL）将死元组标记为可以重用，它也能够截断 table 末尾的死元组，但它不会消除那些死元组。
VACUUM FULL 从头开始重写整个 table，因此在此过程中删除了 dead tuplesgwt，但它需要对 table:
的独占锁定
https://www.postgresql.org/message-id/dcc563d10710021855l7ac247ebv62c5fc44a321ee1f%40mail.gmail.com
如果您有一个大的 table 并且想要在其上 运行 VACUUM FULL 并且能够在此过程中使用它，请考虑使用 https://github.com/reorg/pg_repack/.
我编写了一个单元测试，它修改了 table（INSERT 和 DELETE），然后手动修改 VACUUM 和 ANALYZE 是它，然后我查询 pg_stat_user_tables 以确保 VACUUM 和 ANALYZE 确实有一些效果。
我使用以下 SQL：
select
tbl.relid,
tbl.schemaname,
tbl.n_tup_del,
tbl.n_live_tup,
tbl.n_dead_tup,
tbl.n_mod_since_analyze,
tbl.vacuum_count,
tbl.analyze_count
from
pg_stat_user_tables tbl
where
tbl.relname = lower('...')
and schemaname = current_schema();
对于常规 tables 和
select
tbl.relid,
tbl.schemaname,
tbl.n_tup_del,
tbl.n_live_tup,
tbl.n_dead_tup,
tbl.n_mod_since_analyze,
tbl.vacuum_count,
tbl.analyze_count
from
pg_stat_user_tables tbl
join
pg_namespace nsp
on
tbl.schemaname = nsp.nspname
where
tbl.relname = lower('...')
and nsp.oid = pg_my_temp_schema();
对于临时的。
仍然，当我 运行 我的例子时，我观察到 vacuum_count 和 analyze_count 都是零，并且 table 包含很多死元组，例如：
relid = 913896
schemaname = pg_temp_20
n_tup_del = 10000
n_live_tup = 10000
n_dead_tup = 10000
n_mod_since_analyze = 30000
vacuum_count = 0
analyze_count = 0
这是为什么？
自带的代码示例如下：
package com.example;
import static com.example.AutoCommitMode.COMMIT;
import static com.example.AutoCommitMode.ON;
import static com.example.AutoCommitMode.ROLLBACK;
import static java.lang.String.format;
import static java.util.Arrays.asList;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.List;
import javax.sql.DataSource;
import org.eclipse.jdt.annotation.NonNull;
import org.eclipse.jdt.annotation.Nullable;
import org.postgresql.ds.PGSimpleDataSource;
import org.postgresql.ds.common.BaseDataSource;
import org.testng.Assert;
import org.testng.annotations.DataProvider;
import org.testng.annotations.Test;
public final class PostgreSqlVacuumTest {
private static final String JDBC_URL = "jdbc:postgresql://localhost:5432/postgres?currentSchema=sandbox";
@DataProvider
private static @Nullable Object @NonNull[]@NonNull[] getParameters() {
@NonNull final List<@Nullable Object @NonNull[]> parameters = new ArrayList<>();
parameters.add(new @Nullable Object[] {"A", false, ON});
parameters.add(new @Nullable Object[] {"B", false, COMMIT});
parameters.add(new @Nullable Object[] {"C", false, ROLLBACK});
parameters.add(new @Nullable Object[] {"D", true, ON});
parameters.add(new @Nullable Object[] {"E", true, COMMIT});
parameters.add(new @Nullable Object[] {"F", true, ROLLBACK});
return parameters.toArray(new @Nullable Object @NonNull[0]@NonNull[]);
}
@Test(dataProvider = "getParameters")
@SuppressWarnings({"static-method", "incomplete-switch"})
public void test(@NonNull final String tableName,
final boolean temporary,
final AutoCommitMode mode)
throws SQLException {
final DataSource dataSource = new PGSimpleDataSource();
((BaseDataSource) dataSource).setUrl(JDBC_URL);
try (final Connection conn = dataSource.getConnection("user", "password")) {
try (final Statement stmt = conn.createStatement()) {
try {
stmt.executeUpdate(format("drop table %s", tableName));
} catch (@SuppressWarnings("unused") final SQLException ignored) {
// ignore
}
stmt.executeUpdate(format("create %stable %s (id bigint not null)",
temporary ? "temporary " : "",
tableName));
conn.setAutoCommit(mode.autoCommit);
for (int i = 0; i < 10000; i++) {
stmt.executeUpdate(format("insert into %s (id) values (%d)", tableName, i));
}
stmt.executeUpdate(format("delete from %s", tableName));
for (int i = 0; i < 10000; i++) {
stmt.executeUpdate(format("insert into %s (id) values (%d)", tableName, i));
}
switch (mode) {
case COMMIT:
conn.commit();
break;
case ROLLBACK:
conn.rollback();
break;
}
try (final ResultSet countHolder = stmt.executeQuery(format("select count(*) from %s", tableName))) {
Assert.assertTrue(countHolder.next());
final long count = countHolder.getLong(1);
Assert.assertEquals(count, mode == ROLLBACK ? 0L : 10000L);
Assert.assertFalse(countHolder.next());
}
switch (mode) {
case ON:
stmt.executeUpdate(format("vacuum analyze %s", tableName));
break;
case COMMIT:
case ROLLBACK:
// VACUUM cannot be executed inside a transaction block.
conn.setAutoCommit(true);
try {
stmt.executeUpdate(format("vacuum analyze %s", tableName));
} finally {
conn.setAutoCommit(false);
}
break;
}
diagnose(tableName, temporary, stmt);
}
}
}
private static void diagnose(@NonNull final String tableName,
final boolean temporary,
@NonNull final Statement stmt)
throws SQLException {
final List<String> columns = asList("relid", "schemaname", "n_tup_del", "n_live_tup", "n_dead_tup", "n_mod_since_analyze", "vacuum_count", "analyze_count");
final String diagSql = temporary
? "select\n" +
" tbl.relid,\n" +
" tbl.schemaname,\n" +
" tbl.n_tup_del,\n" +
" tbl.n_live_tup,\n" +
" tbl.n_dead_tup,\n" +
" tbl.n_mod_since_analyze,\n" +
" tbl.vacuum_count,\n" +
" tbl.analyze_count\n" +
"from\n" +
" pg_stat_user_tables tbl\n" +
"join\n" +
" pg_namespace nsp\n" +
"on\n" +
" tbl.schemaname = nsp.nspname\n" +
"where\n" +
" tbl.relname = lower('%s')\n" +
" and nsp.oid = pg_my_temp_schema()"
: "select\n" +
" tbl.relid,\n" +
" tbl.schemaname,\n" +
" tbl.n_tup_del,\n" +
" tbl.n_live_tup,\n" +
" tbl.n_dead_tup,\n" +
" tbl.n_mod_since_analyze,\n" +
" tbl.vacuum_count,\n" +
" tbl.analyze_count\n" +
"from\n" +
" pg_stat_user_tables tbl\n" +
"where\n" +
" tbl.relname = lower('%s')\n" +
" and schemaname = current_schema()";
try (final ResultSet rset = stmt.executeQuery(format(diagSql, tableName))) {
while (rset.next()) {
System.out.println("---------------");
for (final String column : columns) {
System.out.println("\t" + column + " = " + rset.getObject(column));
}
}
}
}
}
enum AutoCommitMode {
ON(true),
COMMIT(false),
ROLLBACK(false),
;
final boolean autoCommit;
AutoCommitMode(final boolean autoCommit) {
this.autoCommit = autoCommit;
}
}
您确定用户（您用来手动 运行 VACUUM 的用户）具有足够的权限吗？ 文档说：
"VACUUM processes every table in the current database that the current user has permission to vacuum"
VACUUM（没有 FULL）将死元组标记为可以重用，它也能够截断 table 末尾的死元组，但它不会消除那些死元组。
VACUUM FULL 从头开始重写整个 table，因此在此过程中删除了 dead tuplesgwt，但它需要对 table:
的独占锁定https://www.postgresql.org/message-id/dcc563d10710021855l7ac247ebv62c5fc44a321ee1f%40mail.gmail.com
如果您有一个大的 table 并且想要在其上 运行 VACUUM FULL 并且能够在此过程中使用它，请考虑使用 https://github.com/reorg/pg_repack/.