Add cb psql query menu.

This is an initial phase of supporting a builtin menu of useful queries
when using `cb psql`. Currently, it only supports predefined queries. To
access this menu, simply enter `:menu` into psql and it will present the
available query options.

Example:

```
Example Team/example-cluster/postgres=> :menu
Cache
  1 – Show cache and index hit rates
Connection Management
  2 – Show connection count by state
  3 – Show connection count by user and application
Extensions
  4 – Show available extensions
  5 – Show installed extensions
Indexes
  6 – Show duplicate indexes
  7 – Show list of indexes
  8 – Show unused indexes
Locks
  9 – Show blocking queries
Query Performance
  10 – Show queries consuming the most system time
  11 – Show queries running over 1 minute
  12 – Show slowest average queries
Size Information
  13 – Show database sizes
  14 – Show table sizes

Type choice and press <Enter> (q to quit):

```

CHANGELOG.md

@@ -5,6 +5,8 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ## [Unreleased]
+### Added
+- `cb psql` now provides a builtin menu of commonly useful queries.
 
 ## [3.4.4] - 2024-01-23
 ### Fixed

src/cb/psql.cr

@@ -1,5 +1,6 @@
 require "./action"
 require "./dirs"
+require "./query_menu/*"
 
 module CB
   class Psql < APIAction
@@ -100,6 +101,7 @@ module CB
       File.open(psqlrc.path, "a") do |f|
         f.puts "\\set ON_ERROR_ROLLBACK interactive"
         f.puts "\\set PROMPT1 '#{psqlpromptname}/%[%033[33;1m%]%x%x%x%[%033[0m%]%[%033[1m%]%/%[%033[0m%]%R%# '"
+        f.puts QueryMenu::Menu.new.render(cluster: c)
       end
 
       psqlrc.path.to_s

src/cb/query_menu/menu.psql.ecr

@@ -0,0 +1,32 @@
+<%- option : Int32 = 1 %>
+<%- @queries.each do |category, queries| -%>
+\echo <%= "#{category.colorize.bold}" %>
+<%- queries.each do |query| -%>
+    \echo '  <%= "#{option} \u2013 #{query.label}" %>'
+    <%- option += 1 -%>
+<%- end -%>
+<%- end -%>
+\echo
+\prompt 'Type choice and press <%= "<Enter>".colorize.bold %> (<%= "q".colorize.bold %> to quit): ' choice
+\echo
+
+<%- option = 1 %>
+SELECT CASE
+<%- @queries.each_value do |queries| -%>
+<%- queries.each do |query| %>
+WHEN :'choice'::text = '<%= option %>' THEN
+'\i `echo <%= query.path %>`'
+'\echo'
+'\i <%= @path %>'
+<%- option += 1 -%>
+<%- end -%>
+<%- end -%>
+WHEN :'choice'::text = 'q'
+THEN '\echo Quitting!'
+ELSE
+'\echo <%= "Error:".colorize.red.bold %> Unknown option! Try again.'
+'\echo'
+'\i <%= @path %>'
+END AS action \gset
+
+:action

src/cb/query_menu/queries.cr

@@ -0,0 +1,98 @@
+require "./query"
+
+module CB::QueryMenu
+  # Cache
+  @[Metadata(label: "Show cache and index hit rates", category: "Cache")]
+  class CacheHitRates < Query
+    ::CB::QueryMenu.embed_sql("#{__DIR__}/sql/cache_hit_rates.sql")
+  end
+
+  #
+  # Connection Management
+  #
+
+  @[Metadata(label: "Show connection count by state", category: "Connection Management")]
+  class ConnectionManagementCountByStates < Query
+    ::CB::QueryMenu.embed_sql("#{__DIR__}/sql/connection_management_count_by_state.sql")
+  end
+
+  @[Metadata(label: "Show connection count by user and application", category: "Connection Management")]
+  class ConnectionManagementCountByUser < Query
+    ::CB::QueryMenu.embed_sql("#{__DIR__}/sql/connection_management_count_by_user_and_application.sql")
+  end
+
+  #
+  # Extensions Queries
+  #
+
+  @[Metadata(label: "Show available extensions", category: "Extensions")]
+  class AvailableExtensions < Query
+    ::CB::QueryMenu.embed_sql("#{__DIR__}/sql/extensions_available.sql")
+  end
+
+  @[Metadata(label: "Show installed extensions", category: "Extensions")]
+  class InstalledExtensions < Query
+    ::CB::QueryMenu.embed_sql("#{__DIR__}/sql/extensions_installed.sql")
+  end
+
+  #
+  # Index Queries
+  #
+
+  @[Metadata(label: "Show duplicate indexes", category: "Indexes")]
+  class IndexesDuplicates < Query
+    ::CB::QueryMenu.embed_sql("#{__DIR__}/sql/indexes_duplicates.sql")
+  end
+
+  @[Metadata(label: "Show list of indexes", category: "Indexes")]
+  class IndexesList < Query
+    ::CB::QueryMenu.embed_sql("#{__DIR__}/sql/indexes_list.sql")
+  end
+
+  @[Metadata(label: "Show unused indexes", category: "Indexes")]
+  class IndexesUnused < Query
+    ::CB::QueryMenu.embed_sql("#{__DIR__}/sql/indexes_unused.sql")
+  end
+
+  #
+  # Locks Queries
+  #
+
+  @[Metadata(label: "Show blocking queries", category: "Locks")]
+  class LocksBlockingQueries < Query
+    ::CB::QueryMenu.embed_sql("#{__DIR__}/sql/locks_blocking_queries.sql")
+  end
+
+  #
+  # Query Performance Queries
+  #
+
+  @[Metadata(label: "Show queries consuming the most system time", category: "Query Performance")]
+  class MostConsumingQueries < Query
+    ::CB::QueryMenu.embed_sql("#{__DIR__}/sql/query_performance_most_consuming_system_time.sql")
+  end
+
+  @[Metadata(label: "Show queries running over 1 minute", category: "Query Performance")]
+  class OverOneMinuteQueries < Query
+    ::CB::QueryMenu.embed_sql("#{__DIR__}/sql/query_performance_over_one_minute.sql")
+  end
+
+  @[Metadata(label: "Show slowest average queries", category: "Query Performance")]
+  class SlowestAverageQueries < Query
+    ::CB::QueryMenu.embed_sql("#{__DIR__}/sql/query_performance_slowest_average.sql")
+  end
+
+  #
+  # Size Information Queries
+  #
+
+  @[Metadata(label: "Show database sizes", category: "Size Information")]
+  class DatabaseSize < Query
+    ::CB::QueryMenu.embed_sql("#{__DIR__}/sql/size_information_database_size.sql")
+  end
+
+  @[Metadata(label: "Show table sizes", category: "Size Information")]
+  class TableSize < Query
+    ::CB::QueryMenu.embed_sql("#{__DIR__}/sql/size_information_table_size.sql")
+  end
+end

src/cb/query_menu/query.cr

@@ -0,0 +1,49 @@
+module CB::QueryMenu
+  annotation Metadata; end
+
+  @[Metadata]
+  abstract class Query
+    @dirname : String
+
+    def initialize(@dirname); end
+
+    def path
+      File.join(@dirname, sql_filename)
+    end
+
+    def write
+      File.open(path, "w") { |file| file << sql }
+    end
+
+    def self.all
+      {{
+        Query.subclasses.map do |query|
+          ann = query.annotation(Metadata)
+          raise "#{query} is missing Metadata annotation" unless ann
+          query
+        end
+      }}.sort_by(&.name)
+    end
+
+    def category
+      {{ @type.annotation(Metadata)[:category] }}.to_s
+    end
+
+    def label
+      {{ @type.annotation(Metadata)[:label] }}.to_s
+    end
+
+    abstract def sql
+    abstract def sql_filename
+  end
+
+  macro embed_sql(path)
+    def sql
+      {{ run("../../tools/embed.cr", path).stringify }}
+    end
+
+    def sql_filename
+      File.basename {{path}}
+    end
+  end
+end

src/cb/query_menu/query_menu.cr

@@ -0,0 +1,30 @@
+require "ecr"
+require "file_utils"
+
+require "./query"
+
+module CB::QueryMenu
+  class Menu
+    private property queries : Hash(String, Array(Query)) = Hash(String, Array(Query)).new([] of Query)
+    private property path : String = ""
+
+    def render(cluster : CB::Model::Cluster) : String
+      temp_dir = "/tmp/crunchy/cli/#{cluster.name}-#{cluster.id}-queries"
+      FileUtils.mkdir_p(temp_dir) unless File.exists? temp_dir
+
+      # Aggregate all queries and group them by category in alphabetical order.
+      @queries = Query.all.map(&.new(temp_dir)).sort_by!(&.category).group_by(&.category)
+
+      # Write the queries to the filesystem.
+      @queries.each_value { |queries| queries.each(&.write) }
+
+      # Render the menu file.
+      query_menu = File.open(File.join(temp_dir, "menu.psql"), mode: "w") do |menu|
+        @path = menu.path
+        menu << ECR.render __DIR__ + "/menu.psql.ecr"
+      end
+
+      "\\set menu '\\\\i #{query_menu.path} '"
+    end
+  end
+end

src/cb/query_menu/sql/cache_hit_rates.sql

@@ -0,0 +1,54 @@
+SELECT
+    cache_rates.schemaname,
+    sizes.name AS "Table Name",
+    cache_rates.ratio AS "Cache Hit Ratio",
+    indexes.ratio AS "Index Hit Ratio",
+    CASE WHEN total_reads.cache_reads > 0 THEN ROUND((cache_rates.cache_reads/total_reads.cache_reads * 100), 2) ELSE 0 END AS "Read Percentage",
+    CASE WHEN rowcount.estimate = -1 THEN 0 ELSE rowcount.estimate END AS "Row Count",
+    CASE WHEN size = 8192 THEN '0 bytes' ELSE pg_size_pretty(size) END AS "Size"
+FROM (
+    SELECT
+        n.nspname AS schemaname,
+        c.relname AS name,
+        pg_table_size(c.oid) AS size
+    FROM pg_class c
+    LEFT JOIN pg_namespace n ON (n.oid = c.relnamespace)
+    WHERE n.nspname NOT IN ('pg_catalog', 'information_schema')
+        AND n.nspname !~ '^pg_toast'
+        AND c.relkind='r'
+) AS sizes
+INNER JOIN (
+    SELECT
+        schemaname,
+        relname,
+        (sum(heap_blks_hit) / nullif(sum(heap_blks_hit) + sum(heap_blks_read), 0) * 100)::int AS ratio,
+        sum(heap_blks_read) AS cache_reads
+    FROM pg_statio_user_tables
+    GROUP BY relname, schemaname) AS cache_rates ON sizes.name = cache_rates.relname
+        AND sizes.schemaname = cache_rates.schemaname
+    INNER JOIN (
+        SELECT sum(heap_blks_read) AS cache_reads
+        FROM pg_statio_user_tables
+    ) AS total_reads ON 1 = 1
+    LEFT JOIN (
+        SELECT
+            schemaname,
+            relname,
+            (sum(idx_blks_hit) / nullif(sum(idx_blks_hit + idx_blks_read),0) * 100)::int AS ratio
+        FROM pg_statio_user_indexes
+        GROUP BY schemaname,relname
+    ) AS indexes ON sizes.name = indexes.relname
+        AND sizes.schemaname = indexes.schemaname
+    LEFT JOIN (
+        SELECT
+            reltuples AS estimate,
+            c.relname AS name,
+            n.nspname AS schemaname
+        FROM pg_class c
+        LEFT JOIN pg_namespace n ON (n.oid = c.relnamespace)
+        WHERE n.nspname NOT IN ('pg_catalog', 'information_schema')
+            AND n.nspname !~ '^pg_toast'
+            AND c.relkind='r'
+    ) AS rowcount ON sizes.name = rowcount.name
+         AND sizes.schemaname = rowcount.schemaname
+ORDER BY size DESC

src/cb/query_menu/sql/connection_management_count_by_state.sql

@@ -0,0 +1,8 @@
+SELECT
+    usename AS user_name,
+    state,
+    count(*) AS connection_count
+FROM pg_stat_activity
+WHERE usename NOT IN ('crunchy_replication', 'crunchy_superuser')
+GROUP BY usename, state
+ORDER BY 3 DESC;

src/cb/query_menu/sql/connection_management_count_by_user_and_application.sql

@@ -0,0 +1,8 @@
+SELECT
+    usename as user_name,
+    application_name,
+    count(*) as connection_count
+FROM pg_stat_activity
+WHERE usename NOT IN ('crunchy_replication', 'crunchy_superuser')
+GROUP BY usename, application_name
+ORDER BY 3 DESC;

src/cb/query_menu/sql/extensions_available.sql

@@ -0,0 +1 @@
+SELECT * FROM pg_available_extensions

src/cb/query_menu/sql/extensions_installed.sql

@@ -0,0 +1 @@
+SELECT * FROM pg_extension;