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md5_password_warningsConfigurationReferencemd5_password_warnings Connections and Authentication 18 Controls whether a WARNING about MD5 password deprecation is produced when a CREATE ROLE or ALTER ROLE statement sets an MD5-encrypted…Configuration · Connections and Authentication md5hashExtensionsExtensionstype for storing 128-bit binary data inline md5hash Data typesData types · Extensions mdbqsExtensionsExtensionsMongoDB-style query support for PostgreSQL jsonb mongodb query-language mdbqt CompatibilityCompatibility · Extensions meanExtensionsExtensionsaggregates and functions for PostgreSQL Server aggregates c custom-aggregates extension functions postgresql postgresql-extension mean Functions and aggregatesFunctions and aggregates · Extensions Measuring Executor Timing OverheadManual ChaptersPG18Measuring Executor Timing Overhead When the query executor is running a statement using EXPLAIN ANALYZE, individual operations are timed as well as showing a summary. The overhead of your sy…Measuring Executor Timing Overhead MechanicsManual ChaptersPG1856.2.1. Mechanics This section describes how to implement native language support in a program or library that is part of the PostgreSQL distribution. Currently, it only applies to C program…Mechanics media_typesExtensionsExtensionsStrongly typed MIME media-type data type for PostgreSQL media-type mime pgrx emi_monorepo Data typesData types · Extensions medianExtensionsExtensionsMedian aggregate function for input sets aggregate median statistics median Functions and aggregatesFunctions and aggregates · Extensions medicationsExtensionsExtensionsmedications extension dependency-closure medications source-only sql medications FeaturesFeatures · Extensions memleak_analyzerExtensionsExtensionsA PostgreSQL extension designed to analyze and localize logical memory leaks inside PostgreSQL backend sessions and background workers. memleak_analyzer MonitoringMonitoring · Extensions MemoryManual ChaptersPG1819.4.1. Memory shared_buffers (integer) Sets the amount of memory the database server uses for shared memory buffers. The default is typically 128 megabytes (128MB), but might be less if you…Memory Memory ManagementManual ChaptersPG1845.3. Memory Management PostgreSQL allocates memory within memory contexts, which provide a convenient method of managing allocations made in many different places that need to live for diff…Memory Management memoryamExtensionsExtensionsIn-memory TableAM implementation memory tableam temporary memoryam FeaturesFeatures · Extensions memstatExtensionsExtensionsMemory context statistics for local and instance backends memory monitoring statistics memstat MonitoringMonitoring · Extensions memvolExtensionsExtensionsMemory units memvol Functions and aggregatesFunctions and aggregates · Extensions MERGEManual ChaptersPG18MERGE MERGE — conditionally insert, update, or delete rows of a table Synopsis [ WITH with_query [, ...] ] MERGE INTO [ ONLY ] target_table_name [ * ] [ [ AS ] target_alias ] USING data_sour…MERGE MERGESQL CommandsReferenceMERGE Queries & Data 15 conditionally insert, update, or delete rows of a table [ WITH with_query [, ...] ] MERGE INTO [ ONLY ] target_table_name [ * ] [ [ AS ] target_alias ] USING data_sou…SQL Commands · Queries & Data Merge Support FunctionsManual ChaptersPG189.23. Merge Support Functions PostgreSQL includes one merge support function that may be used in the RETURNING list of a MERGE command to identify the action taken for each row; see Table 9.…Merge Support Functions merge_actionFunctionsReferencemerge_action Merge Support Functions 17 Returns the merge action command executed for the current row. This will be 'INSERT', 'UPDATE', or 'DELETE'. merge_action ( ) → text Returns the merge…Functions · Merge Support Functions merge_ipsExtensionsExtensionsFunctions to merge IP addresses, ignoring gaps cidr inet network merge_ips Functions and aggregatesFunctions and aggregates · Extensions MERGESManual ChaptersPG1836.15.6. MERGES The MERGES clause, if present, tells the system that it is permissible to use the merge-join method for a join based on this operator. MERGES only makes sense for a binary op…MERGES meson Build TargetsManual ChaptersPG1817.4.4. meson Build Targets Individual build targets can be built using ninja target. When no target is specified, everything except documentation is built. Individual build products can be …meson Build Targets meson setup OptionsManual ChaptersPG1817.4.3. meson setup Options meson setup's command-line options are explained below. This list is not exhaustive (use meson configure --help to get one that is). The options not covered here …meson setup Options Message Data TypesManual ChaptersPG1854.6. Message Data Types This section describes the base data types used in messages. Intn(i) An n-bit integer in network byte order (most significant byte first). If i is specified it is th…Message Data Types Message FlowManual ChaptersPG1854.2. Message Flow This section describes the message flow and the semantics of each message type. (Details of the exact representation of each message appear in Section 54.7.) There are sev…Message Flow Message FormatsManual ChaptersPG1854.7. Message Formats This section describes the detailed format of each message. Each is marked to indicate that it can be sent by a frontend (F), a backend (B), or both (F & B). Notice tha…Message Formats Message-Writing GuidelinesManual ChaptersPG1856.2.2. Message-Writing Guidelines Here are some guidelines for writing messages that are easily translatable. Do not construct sentences at run-time, like: printf("Files were %s.\n", flag ?…Message-Writing Guidelines MessageQueueInternalWait EventsReferenceMessageQueueInternal IPC 10 Waiting for other process to be attached in shared message queue. 11 12 13 Waiting for another process to be attached to a shared message queue. 14 15 16 17 18 19…Wait Events · IPC MessageQueuePutMessageWait EventsReferenceMessageQueuePutMessage IPC 10 Waiting to write a protocol message to a shared message queue. 11 12 13 14 15 16 17 18 19 20 Brief rendezvous is normal when every participant continues to adva…Wait Events · IPC MessageQueueReceiveWait EventsReferenceMessageQueueReceive IPC 10 Waiting to receive bytes from a shared message queue. 11 12 13 14 15 16 17 18 19 20 Brief rendezvous is normal when every participant continues to advance. Investi…Wait Events · IPC MessageQueueSendWait EventsReferenceMessageQueueSend IPC 10 Waiting to send bytes to a shared message queue. 11 12 13 14 15 16 17 18 19 20 Brief rendezvous is normal when every participant continues to advance. Investigate whe…Wait Events · IPC Messaging OverviewManual ChaptersPG1854.1.1. Messaging Overview All communication is through a stream of messages. The first byte of a message identifies the message type, and the next four bytes specify the length of the rest …Messaging Overview metaExtensionsExtensionsNormalized, friendlier system catalog for PostgreSQL pg_meta MonitoringMonitoring · Extensions Meta-CommandsManual ChaptersPG18Meta-Commands Anything you enter in psql that begins with an unquoted backslash is a psql meta-command that is processed by psql itself. These commands make psql more useful for administrati…Meta-Commands meta_triggersExtensionsExtensionsInsert, update and delete triggers for the meta system catalog catalog ddl triggers meta_triggers FeaturesFeatures · Extensions metagrationExtensionsExtensionsMigrate Postgres with Postgres migration pgtap replication metagration Replication and streamsReplication and streams · Extensions MetaphoneManual ChaptersPG18F.16.4. Metaphone Metaphone, like Soundex, is based on the idea of constructing a representative code for an input string. Two strings are then deemed similar if they have the same codes. Th…Metaphone micromanageExtensionsExtensionsexample extension to inject plans planner protobuf query-plan pg_micromanage FeaturesFeatures · Extensions migrationExtensionsExtensionsDatabase Migrations: Configure and Run migration schema versioning postgresql_migrations Replication and streamsReplication and streams · Extensions Migration to Version 18Manual ChaptersPG18E.6.2. Migration to Version 18 A dump/restore using pg_dumpall or use of pg_upgrade or logical replication is required for those wishing to migrate data from any previous release. See Sectio…Migration to Version 18