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hdfs_fdwExtensionsExtensionsforeign-data wrapper for remote hdfs servers hdfs_fdw Foreign data wrappersForeign data wrappers · Extensions Heap FunctionsManual ChaptersPG18F.23.2. Heap Functions heap_page_items(page bytea) returns setof record heap_page_items shows all line pointers on a heap page. For those line pointers that are in use, tuple headers as well…Heap Functions Heap-Only Tuples (HOT)Manual ChaptersPG1866.7. Heap-Only Tuples (HOT) To allow for high concurrency, PostgreSQL uses multiversion concurrency control (MVCC) to store rows. However, MVCC has some downsides for update queries. Specif…Heap-Only Tuples (HOT) heapyExtensionsExtensionstable AM for Yezzey heapy AnalyticsAnalytics · Extensions heightFunctionsReferenceheight Geometric Functions And Operators 10 vertical size of box height ( box ) → double precision vertical size of box 11 12 13 Computes vertical size of box. height ( box ) → double precis…Functions · Geometric Functions And Operators hello-worldExtensionsExtensionsRLS demo extension with users and products tables supabase hello-world SecuritySecurity · Extensions hello_fdwExtensionsExtensionsforeign-data wrapper for hello world example fdw hello-world hello_fdw Foreign data wrappersForeign data wrappers · Extensions hello_pgExtensionsExtensionsMinimal pgrx hello-world extension used to reproduce a macOS build issue. hello_pg Functions and aggregatesFunctions and aggregates · Extensions hello_worldExtensionsExtensionsA simple hello-world Postgres extension using sql/plpgsql implementing a russian roulette function. database.dev tle hello_world Functions and aggregatesFunctions and aggregates · Extensions helloworldtableExtensionsExtensionspgrx example returning a one-row table containing a Hello World greeting. helloworldtable Functions and aggregatesFunctions and aggregates · Extensions hessra_authzExtensionsExtensionsBiscuit-token authorization helpers plus key and service-chain management inside PostgreSQL. authorization biscuit pgrx token hessra_authz SecuritySecurity · Extensions hexgridExtensionsExtensionsConfigurable hex grid on abstract surface hexgrid morton code hexgrid GeospatialGeospatial · Extensions High Availability, Load Balancing, and ReplicationManual ChaptersPG18Chapter 26. High Availability, Load Balancing, and Replication Database servers can work together to allow a second server to take over quickly if the primary server fails (high availability…High Availability, Load Balancing, and Replication Highlighting ResultsManual ChaptersPG1812.3.4. Highlighting Results To present search results it is ideal to show a part of each document and how it is related to the query. Usually, search engines show fragments of the document …Highlighting Results historical_geocodingExtensionsExtensionsSQL toolkit for geocoding historical addresses by combining textual, temporal, and spatial evidence. address geocoding gis historical-data localisation historical_geocoding GeospatialGeospatial · Extensions History of UnitsManual ChaptersPG18B.6. History of Units The SQL standard states that “Within the definition of a ‘datetime literal’, the ‘datetime values’ are constrained by the natural rules for dates and times according to…History of Units hive_fdwExtensionsExtensionsForeign data wrapper for querying Apache Hive from PostgreSQL. fdw hive java jdbc hive_fdw Foreign data wrappersForeign data wrappers · Extensions hllExtensionsExtensionstype for storing hyperloglog data hll FeaturesFeatures · Extensions hmac()Manual ChaptersPG18F.26.1.2. hmac() hmac(data text, key text, type text) returns bytea hmac(data bytea, key bytea, type text) returns bytea Calculates hashed MAC for data with key key. type is the same as in d…hmac() holycornExtensionsExtensionsRuby foreign data wrapper provider fdw foreign-data-wrapper mruby ruby holycorn Foreign data wrappersForeign data wrappers · Extensions Hook TypesManual ChaptersPG1832.20.1.1. Hook Types The following PGauthData types and their corresponding data structures are defined: PQAUTHDATA_PROMPT_OAUTH_DEVICE # Replaces the default user prompt during the builtin…Hook Types hostCommand-line ToolsPG18host Name of host to connect to. If a host name looks like an absolute path name, it specifies Unix-domain communication rather than TCP/IP communication; the value is the name of the direct…Database Connection Control Functions › Parameter Key Words hostFunctionsReferencehost Network Address Functions And Operators 10 extract IP address as text host ( inet ) → text extract IP address as text 11 12 13 Returns the IP address as text, ignoring the netmask. host…Functions · Network Address Functions And Operators Host Variables with Nonprimitive TypesManual ChaptersPG1834.4.4.3. Host Variables with Nonprimitive Types As a host variable you can also use arrays, typedefs, structs, and pointers.Host Variables with Nonprimitive Types hostaddrCommand-line ToolsPG18hostaddr Numeric IP address of host to connect to. This should be in the standard IPv4 address format, e.g., 172.28.40.9. If your machine supports IPv6, you can also use those addresses. TCP…Database Connection Control Functions › Parameter Key Words hostmaskFunctionsReferencehostmask Network Address Functions And Operators 10 construct host mask for network hostmask ( inet ) → inet construct host mask for network 11 12 13 Computes the host mask for the address's…Functions · Network Address Functions And Operators hostnameExtensionsExtensionsGet the server host name gethostbyname host hostname pg_hostname UtilitiesUtilities · Extensions hosts_fileConfigurationReferencehosts_file File Locations 19 Specifies the configuration file for host-based SSL configuration (customarily called pg_hosts.conf). This parameter can only be set at server start. See also Se…Configuration · File Locations Hot StandbyManual ChaptersPG1826.4. Hot Standby Hot standby is the term used to describe the ability to connect to the server and run read-only queries while the server is in archive recovery or standby mode. This is use…Hot Standby Hot Standby Parameter ReferenceManual ChaptersPG1826.4.4. Hot Standby Parameter Reference Various parameters have been mentioned above in Section 26.4.2 and Section 26.4.3. On the primary, the wal_level parameter can be used. max_standby_ar…Hot Standby Parameter Reference hot_standbyConfigurationReferencehot_standby Replication 10 Specifies whether or not you can connect and run queries during recovery, as described in Section 26.5. The default value is on. This parameter can only be set at …Configuration · Replication hot_standby_feedbackConfigurationReferencehot_standby_feedback Replication 10 Specifies whether or not a hot standby will send feedback to the primary or upstream standby about queries currently executing on the standby. This parame…Configuration · Replication How Connections Are EstablishedManual ChaptersPG1851.2. How Connections Are Established PostgreSQL implements a “process per user” client/server model. In this model, every client process connects to exactly one backend process. As we do no…How Connections Are Established How Extensibility WorksManual ChaptersPG1836.1. How Extensibility Works PostgreSQL is extensible because its operation is catalog-driven. If you are familiar with standard relational database systems, you know that they store inform…How Extensibility Works How It WorksManual ChaptersPG18How It Works The basic idea is to have a replication start point from the source server and set up a logical replication to start from this point: Start the target server with the specified …How It Works How It WorksManual ChaptersPG18How It Works The basic idea is to copy all file system-level changes from the source cluster to the target cluster: Scan the WAL log of the target cluster, starting from the last checkpoint …How It Works How Parallel Query WorksManual ChaptersPG1815.1. How Parallel Query Works When the optimizer determines that parallel query is the fastest execution strategy for a particular query, it will create a query plan that includes a Gather …How Parallel Query Works How SELECT Rules WorkManual ChaptersPG1839.2.1. How SELECT Rules Work Rules ON SELECT are applied to all queries as the last step, even if the command given is an INSERT, UPDATE or DELETE. And they have different semantics from ru…How SELECT Rules Work How the Planner Uses StatisticsManual ChaptersPG18Chapter 69. How the Planner Uses Statistics This chapter builds on the material covered in Section 14.1 and Section 14.2 to show some additional details about how the planner uses the system…How the Planner Uses Statistics How to Use ItManual ChaptersPG18F.9.2. How to Use It Here's a simple example of usage: CREATE TABLE users ( nick CITEXT PRIMARY KEY, pass TEXT NOT NULL ); INSERT INTO users VALUES ( 'larry', sha256(random()::text::bytea) )…How to Use It