{"id":4219,"date":"2025-06-15T09:37:05","date_gmt":"2025-06-15T09:37:05","guid":{"rendered":"https:\/\/w3buddy.com\/?post_type=cposts&p=4219"},"modified":"2026-09-26T13:08:08","modified_gmt":"2026-09-26T07:38:08","slug":"opening-a-physical-standby-database","status":"publish","type":"post","link":"https:\/\/w3buddy.com\/blog\/opening-a-physical-standby-database\/","title":{"rendered":"Opening a Physical Standby Database"},"content":{"rendered":"\n

1. Real-time Query<\/h2>\n\n\n\n

What is Real-time Query?<\/h3>\n\n\n\n

Real-time Query<\/strong> allows you to run read-only queries<\/strong> on a physical standby database<\/strong> while redo apply is running in the background<\/strong>.<\/p>\n\n\n\n

This means your standby can serve reporting and analytics workloads<\/strong> in real-time<\/strong>, offloading the primary database and maximizing resource usage.<\/p>\n\n\n\n

\n

\ud83c\udff7\ufe0f This feature is available only with Oracle Active Data Guard (licensed)<\/strong>.<\/p>\n<\/blockquote>\n\n\n\n

Why Use Real-time Query?<\/h3>\n\n\n\n
Benefit<\/th>Explanation<\/th><\/tr><\/thead>
\u2705 Reporting on standby<\/td>Run reports without affecting primary DB<\/td><\/tr>
\u2705 Real-time data access<\/td>Queries see changes as redo is applied<\/td><\/tr>
\u2705 High availability<\/td>Offload workload and still be disaster-ready<\/td><\/tr>
\u2705 RAC support<\/td>Can use Oracle RAC on the standby too<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

Requirements Before You Start<\/h3>\n\n\n\n
Requirement<\/th>Detail<\/th><\/tr><\/thead>
Oracle Edition<\/td>Enterprise Edition with Active Data Guard license<\/td><\/tr>
Compatible Parameter<\/td>Must be 11.0.0<\/code> or higher<\/td><\/tr>
Role<\/td>Physical standby only (not logical)<\/td><\/tr>
Redo Transport<\/td>SYNC<\/strong> mode recommended for accuracy<\/td><\/tr>
Archive Log<\/td>Database must be in ARCHIVELOG<\/code> mode<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

Steps to Enable Real-time Query<\/h3>\n\n\n\n

Here\u2019s how you can enable real-time query on a physical standby:<\/p>\n\n\n\n

Step-by-step Guide<\/h4>\n\n\n\n
-- 1. Cancel managed recovery (stop redo apply)\nALTER DATABASE RECOVER MANAGED STANDBY DATABASE CANCEL;\n\n-- 2. Open standby database in read-only mode\nALTER DATABASE OPEN;\n\n-- 3. Restart redo apply in background (real-time apply)\nALTER DATABASE RECOVER MANAGED STANDBY DATABASE DISCONNECT;<\/code><\/code><\/pre>\n\n\n\n
\n
\ud83d\udca1 Now your standby is open for read-only access<\/strong> and applying redo<\/strong> at the same time \u2014 this is called \u201cReal-time Query mode\u201d<\/strong>.<\/p>\n<\/blockquote>\n\n\n\n
How to Check if It\u2019s Working<\/h3>\n\n\n\n
SELECT open_mode FROM V$DATABASE;<\/code><\/code><\/pre>\n\n\n\n
Expected Result:<\/p>\n\n\n\n
OPEN_MODE<\/th>Meaning<\/th><\/tr><\/thead>
READ ONLY WITH APPLY<\/td>Standby is open and applying redo<\/td><\/tr>
READ ONLY<\/td>Open, but not applying redo<\/td><\/tr>
MOUNTED<\/td>Not open for queries<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
Monitor Apply Lag (How behind is the standby?)<\/h3>\n\n\n\n
SELECT name, value, datum_time, time_computed \nFROM V$DATAGUARD_STATS \nWHERE name = 'apply lag';<\/code><\/code><\/pre>\n\n\n\n
This tells you how much delay<\/strong> exists between the primary and standby.<\/p>\n\n\n\n
Control Query Freshness with STANDBY_MAX_DATA_DELAY<\/h3>\n\n\n\n
By default, Oracle lets you query even if the standby is slightly behind. But you can control how “fresh” the data must be<\/strong>.<\/p>\n\n\n\n
Value<\/th>Effect<\/th><\/tr><\/thead>
NONE<\/code> (default)<\/td>No delay check \u2014 show whatever is there<\/td><\/tr>
0<\/code><\/td>Query only if standby is 100% up-to-date<\/td><\/tr>
n<\/code> (in seconds)<\/td>Allow queries if lag is under n<\/code> seconds<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
\ud83d\udd27 Example:<\/h4>\n\n\n\n
ALTER SESSION SET STANDBY_MAX_DATA_DELAY = 3;<\/code><\/code><\/pre>\n\n\n\n
This tells Oracle: “Let me run the query only if the data is at most 3 seconds old<\/strong>.”<\/p>\n\n\n\n
\n
\u26a0\ufe0f If not satisfied, Oracle throws: ORA-03172: standby data not consistent<\/code><\/p>\n<\/blockquote>\n\n\n\n
Want to Wait Until Standby Catches Up?<\/h3>\n\n\n\n
You can force the session to wait until standby is caught up<\/strong>:<\/p>\n\n\n\n
ALTER SESSION SYNC WITH PRIMARY;<\/code><\/code><\/pre>\n\n\n\n
This is useful if you’re okay to wait a bit<\/strong> and want guaranteed consistency<\/strong>.<\/p>\n\n\n\n
You can also automate this with a trigger<\/strong>, like so:<\/p>\n\n\n\n
CREATE TRIGGER adg_logon_sync_trigger\nAFTER LOGON ON SCHEMA\nBEGIN\n  IF SYS_CONTEXT('USERENV','DATABASE_ROLE') = 'PHYSICAL STANDBY' THEN\n    EXECUTE IMMEDIATE 'ALTER SESSION SYNC WITH PRIMARY';\n  END IF;\nEND;<\/code><\/code><\/pre>\n\n\n\n
What if Data Block is Corrupted?<\/h3>\n\n\n\n
Real-time query supports automatic block media recovery<\/strong>. If a block is corrupted, Oracle fetches a good copy from the primary<\/strong> automatically.<\/p>\n\n\n\n
Manual Recovery (if needed):<\/h4>\n\n\n\n
RECOVER BLOCK FOR FILE 5 BLOCK 1234;<\/code><\/code><\/pre>\n\n\n\n
Real-time Query: Important Notes<\/h3>\n\n\n\n
Note<\/th>Description<\/th><\/tr><\/thead>
Real-time apply must be running<\/td>Otherwise queries won\u2019t see latest data<\/td><\/tr>
SYNC is better<\/td>For best accuracy and consistency<\/td><\/tr>
Only physical standby supported<\/td>Logical standby doesn\u2019t support real-time apply<\/td><\/tr>
Requires Active Data Guard<\/td>Needs additional license<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
\u2705 Summary<\/h3>\n\n\n\n
Feature<\/th>Real-time Query<\/th><\/tr><\/thead>
Allows read-only queries on standby<\/td>\u2705 Yes<\/td><\/tr>
Redo Apply continues in background<\/td>\u2705 Yes<\/td><\/tr>
Data freshness control<\/td>\u2705 With STANDBY_MAX_DATA_DELAY<\/code><\/td><\/tr>
Auto block repair<\/td>\u2705 Yes<\/td><\/tr>
Licensing required<\/td>\u2705 Active Data Guard<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
2. Using SQL and PL\/SQL on Active Data Guard Standbys<\/h2>\n\n\n\n
What\u2019s New in 19c?<\/h3>\n\n\n\n
Starting with Oracle 19c<\/strong>, Active Data Guard now allows SQL and PL\/SQL operations<\/strong> on physical standby databases \u2014 including DML<\/strong> and top-level PL\/SQL blocks<\/strong>.<\/p>\n\n\n\n
This means you can now:<\/p>\n\n\n\n
    \n
  • Perform occasional inserts, updates, and deletes<\/strong><\/li>\n\n\n\n
  • Run PL\/SQL procedures\/functions<\/strong><\/li>\n\n\n\n
  • Automatically recompile invalid PL\/SQL objects<\/strong><\/li>\n<\/ul>\n\n\n\n
    \n
    \u26a0\ufe0f But remember \u2014 these operations are redirected to the primary<\/strong>, not executed on the standby itself.<\/p>\n<\/blockquote>\n\n\n\n
    \ud83d\udd0d Why Allow DML & PL\/SQL on a Standby?<\/h2>\n\n\n\n
    Advantage<\/th>Description<\/th><\/tr><\/thead>
    \u2705 Read-mostly apps supported<\/td>Ideal for apps that mostly read but occasionally write<\/td><\/tr>
    \u2705 Query + small write support<\/td>You don\u2019t need to switch over to primary<\/td><\/tr>
    \u2705 Simplifies development<\/td>Developers can work on the standby with fewer restrictions<\/td><\/tr>
    \u2705 Automatic redirection<\/td>Oracle forwards changes to the primary for you<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
    DML Operations on Active Data Guard Standby<\/h2>\n\n\n\n
    How Does It Work?<\/h3>\n\n\n\n
      \n
    • DML (e.g. INSERT<\/code>, UPDATE<\/code>, DELETE<\/code>) is automatically forwarded<\/strong> to the primary database<\/strong><\/li>\n\n\n\n
    • The standby waits<\/strong> for the change to be applied<\/li>\n\n\n\n
    • Read consistency is maintained<\/strong> (you can see your own uncommitted changes)<\/li>\n<\/ul>\n\n\n\n
      \n
      This is useful for interactive dashboards<\/strong>, minor edits, or mixed workloads.<\/p>\n<\/blockquote>\n\n\n\n
      Setup: Enable DML Redirection<\/h3>\n\n\n\n
      Level<\/th>Method<\/th><\/tr><\/thead>
      System-level (global)<\/td>ALTER SYSTEM SET ADG_REDIRECT_DML = TRUE;<\/code> (requires restart)<\/em><\/td><\/tr>
      Session-level (preferred for testing)<\/td>ALTER SESSION ENABLE ADG_REDIRECT_DML;<\/code><\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
      Example<\/h4>\n\n\n\n
      -- On the standby\nALTER SESSION ENABLE ADG_REDIRECT_DML;\n\n-- Run a DML\nINSERT INTO employees VALUES (201, 'John', 'Doe', 5000);<\/code><\/code><\/pre>\n\n\n\n
      \u2705 This DML is sent to primary<\/strong>, executed there, and the result is shipped back.<\/p>\n\n\n\n
      \n
      Until committed on the primary, only this session<\/strong> sees the change. Other sessions on standby will see it after commit<\/strong>.<\/p>\n<\/blockquote>\n\n\n\n
      DML: Best Practices & Warnings<\/h3>\n\n\n\n
      Point<\/th>Detail<\/th><\/tr><\/thead>
      \u274c Avoid heavy DMLs<\/td>Too many writes on standby = overhead on primary<\/td><\/tr>
      \ud83d\udeab No XA transactions<\/td>Distributed transactions (XA) are not supported<\/td><\/tr>
      \ud83d\udd04 Use session-level config for safety<\/td>Avoid making it default unless needed<\/td><\/tr>
      \u2705 Great for small, low-impact writes<\/td>Think: logging, bookmarks, temp notes, etc.<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
      PL\/SQL Execution on Standby<\/h2>\n\n\n\n
      You can now run top-level PL\/SQL blocks<\/strong> (procedures\/functions) on Active Data Guard standby.<\/p>\n\n\n\n
      These too are automatically redirected<\/strong> to the primary<\/strong>.<\/p>\n\n\n\n
      \n
      \ud83d\udca1 \u201cTop-level\u201d means: directly run blocks \u2014 not anonymous PL\/SQL inside SQL tools.<\/p>\n<\/blockquote>\n\n\n\n
      Enabling PL\/SQL Redirection<\/h3>\n\n\n\n
      ALTER SESSION ENABLE ADG_REDIRECT_PLSQL;<\/code><\/code><\/pre>\n\n\n\n
      \ud83d\udd39 Only works at the session level<\/strong>
      \ud83d\udd39 Only for top-level calls<\/strong> (not dynamic SQL or bind variables)<\/p>\n\n\n\n
      PL\/SQL Example<\/h3>\n\n\n\n
      -- Assume this procedure exists on both primary & standby\nCREATE OR REPLACE PROCEDURE update_sal (\n  emp_id IN NUMBER,\n  sal IN NUMBER\n) AS\nBEGIN\n  UPDATE employees SET salary = sal WHERE employee_id = emp_id;\nEND;<\/code><\/code><\/pre>\n\n\n\n
      Use it on the standby:<\/h4>\n\n\n\n
      ALTER SESSION ENABLE ADG_REDIRECT_DML;  -- Required if PL\/SQL uses DML\nALTER SESSION ENABLE ADG_REDIRECT_PLSQL;\n\nEXEC update_sal(105, 6000);<\/code><\/code><\/pre>\n\n\n\n
      \u2705 Oracle will redirect the call to the primary, execute it, and return the result.<\/p>\n\n\n\n
      Automatic Recompilation of Invalid PL\/SQL Objects<\/h2>\n\n\n\n
      If a PL\/SQL object becomes invalid<\/strong> (e.g., because of a table change), Oracle can recompile it automatically<\/strong> on the primary \u2014 even from the standby<\/strong>.<\/p>\n\n\n\n
      How It Works<\/h3>\n\n\n\n
        \n
      • The PL\/SQL is invalid<\/li>\n\n\n\n
      • You attempt to use it on standby<\/li>\n\n\n\n
      • Oracle redirects the recompilation to the primary<\/strong><\/li>\n\n\n\n
      • When done, it ships back the valid object<\/li>\n<\/ul>\n\n\n\n
        Requirement<\/h3>\n\n\n\n
        -- Must be enabled to allow this:\nALTER SYSTEM SET ADG_REDIRECT_DML = TRUE;<\/code><\/code><\/pre>\n\n\n\n
        Recompilation Example<\/h3>\n\n\n\n
        Suppose the update_sal<\/code> procedure becomes invalid due to a table change:<\/p>\n\n\n\n
        -- Table altered on primary:\nALTER TABLE employees ADD COLUMN department_id NUMBER;\n\n-- On standby\nALTER SESSION ENABLE ADG_REDIRECT_DML;\nEXEC update_sal(105, 6000);  -- Automatically recompiles on primary, then executes<\/code><\/code><\/pre>\n\n\n\n
        Oracle detects the invalid PL\/SQL, redirects the DDL<\/strong>, recompiles, and then executes your call.<\/p>\n\n\n\n
        \u2705 Summary Table<\/h2>\n\n\n\n
        Feature<\/th>Supported<\/th>Notes<\/th><\/tr><\/thead>
        DML Redirection<\/td>\u2705<\/td>Auto-forwards to primary<\/td><\/tr>
        PL\/SQL Redirection<\/td>\u2705<\/td>Top-level only, no binds<\/td><\/tr>
        Automatic PL\/SQL Recompilation<\/td>\u2705<\/td>Triggered on first use<\/td><\/tr>
        XA Transactions<\/td>\u274c<\/td>Not supported<\/td><\/tr>
        Mass Writes<\/td>\ud83d\udeab Not Recommended<\/td>Use for small, occasional writes<\/td><\/tr>
        Licensing<\/td>\u2714\ufe0f Requires Active Data Guard<\/td>Oracle EE + license<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
        3. Using Temporary Tables on Active Data Guard Instances<\/h2>\n\n\n\n
        What Are Temporary Tables?<\/h3>\n\n\n\n
        Temporary tables<\/strong> are special tables used to hold session-specific or transaction-specific data. Data in these tables is:<\/p>\n\n\n\n
          \n
        • Private to your session<\/strong><\/li>\n\n\n\n
        • Automatically deleted<\/strong> after a session or transaction ends<\/li>\n\n\n\n
        • Not written to disk permanently<\/strong><\/li>\n\n\n\n
        • Perfect for reporting<\/strong>, intermediate calculations<\/strong>, or scratch work<\/strong><\/li>\n<\/ul>\n\n\n\n
          \ud83d\udd04 Types of Temporary Tables<\/h2>\n\n\n\n
          Type<\/th>Description<\/th>Lifetime<\/th>Where Stored<\/th><\/tr><\/thead>
          Global Temporary Tables (GTTs)<\/strong><\/td>Metadata is stored in the data dictionary; rows are session- or transaction-specific<\/td>Session or transaction<\/td>Disk + memory<\/td><\/tr>
          Private Temporary Tables (PTTs)<\/strong><\/td>Metadata & data stored in memory only<\/strong><\/td>Session<\/td>Memory only<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
          \u2705 Can We Use These on Active Data Guard (ADG)?<\/h2>\n\n\n\n
          Yes! Starting with Oracle 12c and enhanced in 19c+, you can create and use:<\/p>\n\n\n\n
          Table Type<\/th>Supported on ADG?<\/th>Notes<\/th><\/tr><\/thead>
          Global Temporary Tables<\/td>\u2705<\/td>Full DML & DDL supported<\/td><\/tr>
          Private Temporary Tables<\/td>\u2705<\/td>Metadata stored in memory; safe on read-only standby<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
          Global Temporary Tables (GTT) on ADG<\/h2>\n\n\n\n
          DML on GTT: How It Works<\/h3>\n\n\n\n
          Even though ADG is read-only<\/strong>, Oracle allows DML on GTTs because it uses a feature called Temporary Undo<\/strong>.<\/p>\n\n\n\n
          \ud83d\udccc Key Concept: Temporary Undo<\/h3>\n\n\n\n
          Feature<\/th>Description<\/th><\/tr><\/thead>
          What is it?<\/td>Stores undo for temporary tables in the temp tablespace<\/strong>, not undo tablespace<\/td><\/tr>
          Why allowed?<\/td>Doesn’t generate redo<\/strong> \u2192 safe on standby<\/td><\/tr>
          Where is it always enabled?<\/td>Always ON in ADG standby<\/strong><\/td><\/tr>
          How to enable on Primary?<\/td>Set TEMP_UNDO_ENABLED = TRUE<\/code><\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
          \n
          \u2705 This reduces redo traffic<\/strong> and improves performance for both primary and standby.<\/p>\n<\/blockquote>\n\n\n\n
          Example: DML on Global Temporary Table<\/h3>\n\n\n\n
          -- On the ADG standby\nCREATE GLOBAL TEMPORARY TABLE temp_sales (\n   id NUMBER, \n   amount NUMBER\n) ON COMMIT PRESERVE ROWS;\n\n-- Insert data (allowed!)\nINSERT INTO temp_sales VALUES (1, 1000);<\/code><\/code><\/pre>\n\n\n\n
          \u2705 Works perfectly! Data is session-specific<\/strong> and no redo is generated.<\/p>\n\n\n\n
          Benefits of Temporary Undo on ADG<\/h3>\n\n\n\n
          Benefit<\/th>Description<\/th><\/tr><\/thead>
          \u2705 Less redo on primary<\/td>Because temporary undo isn\u2019t logged in redo<\/td><\/tr>
          \u2705 Less network usage<\/td>Less redo to ship to standby<\/td><\/tr>
          \u2705 Supports reporting apps<\/td>Useful for BI tools or temporary staging logic<\/td><\/tr>
          \u2705 Fast scratch space<\/td>Without permanent writes to disk<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
          Restrictions on GTT in ADG<\/h3>\n\n\n\n
          Limitation<\/th>Explanation<\/th><\/tr><\/thead>
          \ud83d\udd12 COMPATIBLE >= 12.0.0<\/code> required<\/td>For temporary undo feature<\/td><\/tr>
          \ud83d\udeab No temp BLOBs\/CLOBs<\/td>Unsupported<\/td><\/tr>
          \ud83d\udeab No distributed transactions with GTT<\/td>Can\u2019t modify GTT and remote DB in same transaction<\/td><\/tr>
          \u26a0\ufe0f EXPLAIN PLAN<\/code> uses GTT internally<\/td>May conflict with remote DML in same session<\/td><\/tr>
          \u274c TEMP_UNDO_ENABLED has no effect on standby<\/td>It\u2019s always ON automatically<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
          DDL on GTTs: Create\/Drop<\/h2>\n\n\n\n
          You can issue CREATE<\/strong> and DROP<\/strong> GTT statements from the ADG standby.<\/p>\n\n\n\n
          These are redirected<\/strong> to the primary<\/strong>, executed there, and reflected back<\/strong>.<\/p>\n\n\n\n
          \n
          \ud83d\udd01 Managed recovery must be in real-time apply mode<\/strong> and standby must be in sync<\/strong>.<\/p>\n<\/blockquote>\n\n\n\n
          Example: Create GTT on ADG<\/h3>\n\n\n\n
          -- On standby, create table\nCREATE GLOBAL TEMPORARY TABLE temp_orders (\n   order_id NUMBER, \n   region VARCHAR2(20)\n) ON COMMIT PRESERVE ROWS;<\/code><\/code><\/pre>\n\n\n\n
          \u2705 Oracle transparently redirects this DDL to the primary, executes it, and reflects the change to the standby.<\/p>\n\n\n\n
          \ud83d\udd12 Note on DDL Redirection<\/h2>\n\n\n\n
          Condition<\/th>Requirement<\/th><\/tr><\/thead>
          \ud83d\udfe2 Standby apply must be running<\/td>With real-time apply<\/strong> enabled<\/td><\/tr>
          \ud83d\udfe2 Standby must be synced<\/strong> with primary<\/td>No large lag<\/td><\/tr>
          \ud83d\udee0\ufe0f Still can do DDL from primary<\/td>ADG standby sees it when caught up<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
          Private Temporary Tables (PTT) on ADG<\/h2>\n\n\n\n
          What Makes PTTs Special?<\/h3>\n\n\n\n
          Feature<\/th>Description<\/th><\/tr><\/thead>
          \u2705 Fully in-memory<\/td>No disk metadata \u2192 OK on read-only DB<\/td><\/tr>
          \ud83d\udd12 Session-bound<\/td>Auto-dropped when session ends<\/td><\/tr>
          \ud83d\udd27 Lightweight<\/td>Ideal for quick calculations or filtering<\/td><\/tr>
          \ud83c\udd95 Introduced in<\/td>Oracle 18c<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
          Example: Create PTT on ADG<\/h3>\n\n\n\n
          -- On ADG standby\nCREATE PRIVATE TEMPORARY TABLE ora$ptt_sales (\n   product_id NUMBER,\n   amount NUMBER\n);<\/code><\/code><\/pre>\n\n\n\n
          \u2705 No redo, no disk writes \u2014 safe and fast on ADG.<\/p>\n\n\n\n
          \n
          \u2757Table names must start with ORA$PTT_<\/code> or ORA$<\/code> by default<\/p>\n<\/blockquote>\n\n\n\n
          Quick Feature Summary Table<\/h2>\n\n\n\n
          Feature<\/th>GTT<\/th>PTT<\/th><\/tr><\/thead>
          Allowed on ADG?<\/td>\u2705 Yes<\/td>\u2705 Yes<\/td><\/tr>
          Undo generates redo?<\/td>\u274c No (stored in temp tablespace)<\/td>\u274c No (in-memory)<\/td><\/tr>
          Metadata stored?<\/td>\u2705 On disk<\/td>\u274c In memory only<\/td><\/tr>
          Supports DML?<\/td>\u2705 Yes<\/td>\u2705 Yes<\/td><\/tr>
          Auto dropped?<\/td>\u274c No (must drop manually)<\/td>\u2705 Yes (end of session)<\/td><\/tr>
          Requires TEMP_UNDO_ENABLED?<\/td>\u2705 (on primary)<\/td>\u274c Not needed<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
          \ud83d\udcccSummary: Best Practices<\/h2>\n\n\n\n
          Task<\/th>Recommendation<\/th><\/tr><\/thead>
          Use GTTs for heavy reporting apps<\/td>\u2705 Ideal for session temp staging<\/td><\/tr>
          Prefer PTTs for one-off analytics or filters<\/td>\u2705 Very fast & in-memory<\/td><\/tr>
          Always keep standby in sync<\/td>\u2705 Required for DDL redirection<\/td><\/tr>
          Avoid BLOB\/CLOB in GTTs<\/td>\u274c Not supported<\/td><\/tr>
          Avoid distributed transactions + GTT<\/td>\u26a0\ufe0f Causes errors<\/td><\/tr>
          Use real-time apply mode<\/td>\u2705 Required for DDL visibility on standby<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
          4. IM Column Store in an Active Data Guard Environment<\/h2>\n\n\n\n
          What Is the IM Column Store?<\/h3>\n\n\n\n
          The In-Memory Column Store (IM column store)<\/strong> is a feature that stores table data in a compressed columnar format in memory<\/strong>, enabling super-fast analytical queries and reporting by scanning only the relevant columns.<\/p>\n\n\n\n
          Starting with Oracle 12c Release 2 (12.2.0.1)<\/strong>, Oracle supports the IM column store<\/strong> on Active Data Guard (ADG) standby databases<\/strong>.<\/p>\n\n\n\n
          Why Use IM Column Store on ADG?<\/h2>\n\n\n\n
          Using the IM column store on a standby database has several key benefits:<\/p>\n\n\n\n
          Benefit<\/th>Description<\/th><\/tr><\/thead>
          \ud83d\udd04 Offload Analytics<\/td>Run reporting workloads directly on the standby, reducing load on the primary<\/td><\/tr>
          \u26a1 Faster Query Performance<\/td>Columnar format allows fast scans, filters, and aggregations<\/td><\/tr>
          \ud83d\udce6 Double Memory Utilization<\/td>You can populate different data sets<\/strong> in the primary and standby IM stores, effectively doubling IM memory usage across both<\/td><\/tr>
          \ud83d\udcbe Reduced I\/O<\/td>Since data is in memory, disk access is minimized<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
          Configuration Steps<\/h2>\n\n\n\n
          Step<\/th>Description<\/th><\/tr><\/thead>
          1\ufe0f\u20e3 Ensure version is 12.2.0.1 or above<\/td>IM support on ADG begins from this version<\/td><\/tr>
          2\ufe0f\u20e3 Configure memory for IM column store<\/td>Use INMEMORY_SIZE<\/code> parameter on both primary and standby<\/td><\/tr>
          3\ufe0f\u20e3 On standby, set parameter for MIRA support<\/td>ENABLE_IMC_WITH_MIRA = TRUE<\/code> if using multi-instance redo apply (RAC)<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
          Example Configuration (Simplified)<\/h3>\n\n\n\n
          -- On standby database\nALTER SYSTEM SET INMEMORY_SIZE = 2G SCOPE=SPFILE;\nALTER SYSTEM SET ENABLE_IMC_WITH_MIRA = TRUE SCOPE=BOTH;\n\n-- Restart the standby instance to activate IM column store<\/code><\/code><\/pre>\n\n\n\n
          Practical Benefits in an ADG Setup<\/h2>\n\n\n\n
          Scenario<\/th>Value<\/th><\/tr><\/thead>
          \ud83e\uddfe Heavy BI reporting on standby<\/td>Leverages in-memory scanning speed<\/td><\/tr>
          \ud83d\udcca Different IM population on standby<\/td>Run standby-specific analytics<\/td><\/tr>
          \ud83e\udde0 Free up primary memory<\/td>Offload less-used datasets to standby’s IM store<\/td><\/tr>
          \ud83e\uddea Test new in-memory strategies<\/td>Use standby as a low-risk experimentation ground<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
          Limitations to Be Aware Of<\/h2>\n\n\n\n
          Limitation<\/th>Description<\/th><\/tr><\/thead>
          \ud83d\udeab In-Memory Expressions<\/td>Only learned from queries run on primary<\/strong><\/td><\/tr>
          \ud83d\udeab In-Memory ILM policies<\/td>Triggered only by primary activity<\/strong><\/td><\/tr>
          \ud83d\udeab In-Memory FastStart<\/td>\u274c Not supported on standby<\/td><\/tr>
          \ud83d\udeab In-Memory Join Groups<\/td>\u274c Not supported on standby<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
          \ud83d\udd0d Summary Table<\/h2>\n\n\n\n
          Feature<\/th>Supported on ADG Standby?<\/th>Notes<\/th><\/tr><\/thead>
          IM Column Store<\/td>\u2705 Yes<\/td>From Oracle 12.2 onwards<\/td><\/tr>
          Different IM contents per DB<\/td>\u2705 Yes<\/td>Great for load balancing<\/td><\/tr>
          In-Memory Expressions<\/td>\u274c No<\/td>Only primary learns expressions<\/td><\/tr>
          ILM policies<\/td>\u274c No<\/td>Only primary tracks access<\/td><\/tr>
          In-Memory FastStart<\/td>\u274c No<\/td>Not supported<\/td><\/tr>
          In-Memory Join Groups<\/td>\u274c No<\/td>Not supported<\/td><\/tr>
          MIRA (Multi-Instance Redo Apply) support<\/td>\u2705 Yes<\/td>Set ENABLE_IMC_WITH_MIRA = TRUE<\/code><\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
          \u2705 Best Practices<\/h2>\n\n\n\n
          Task<\/th>Recommendation<\/th><\/tr><\/thead>
          Enable IM column store on standby<\/td>\u2705 For high-speed analytics<\/td><\/tr>
          Use different IM contents<\/td>\u2705 To maximize memory usage<\/td><\/tr>
          Monitor ADG lag<\/td>\u2705 To ensure real-time reporting accuracy<\/td><\/tr>
          Avoid relying on ILM or Join Groups<\/td>\u274c These are not supported on standby<\/td><\/tr>
          Use for read-mostly, reporting, and BI<\/td>\u2705 Ideal workload on ADG standby<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
          5. In-Memory External Tables in an Active Data Guard Environment<\/h2>\n\n\n\n
          What Are In-Memory External Tables?<\/h3>\n\n\n\n
          In-Memory External Tables<\/strong> combine the speed of Oracle In-Memory (IM) column store<\/strong> with the flexibility of external tables<\/strong> (tables that reference data outside the database\u2014e.g., flat files on disk). They allow high-speed analytics on external data<\/strong> as if it’s part of the database, using in-memory columnar format.<\/p>\n\n\n\n
          With Active Data Guard<\/strong>, this feature is now available on standby databases<\/strong> as well\u2014great for offloading analytics<\/strong> from primary!<\/p>\n\n\n\n
          Benefits in ADG Environment<\/h2>\n\n\n\n
          Benefit<\/th>Description<\/th><\/tr><\/thead>
          \ud83d\udd04 Query Offloading<\/td>Run external table queries on standby instead of primary<\/td><\/tr>
          \u26a1 Parallel Load & Query<\/td>External data is loaded in parallel<\/strong> into IM column store for fast querying<\/td><\/tr>
          \ud83e\udde0 Columnar Analytics<\/td>Uses compressed column format for fast filtering, scans, and joins<\/td><\/tr>
          \ud83d\udcbd Less Disk I\/O<\/td>Queries are satisfied from memory rather than disk reads<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
          Key Behavior & Configuration Notes<\/h2>\n\n\n\n
          Feature<\/th>Description<\/th><\/tr><\/thead>
          \u2705 Supported in ADG<\/td>In-memory external tables can be queried on the standby<\/td><\/tr>
          \u2699\ufe0f Parallel Query<\/td>External table segments are loaded in parallel<\/strong> on both primary and standby<\/td><\/tr>
          \ud83d\udd01 IM Segment Behavior<\/td>Using INMEMORY<\/code> or NO INMEMORY<\/code> can release or control IM segment usage on standby<\/td><\/tr>
          \u274c FOR SERVICE Subclause Not Supported<\/td>The FOR SERVICE<\/code> clause in INMEMORY ... DISTRIBUTE<\/code> is not supported<\/strong> on primary or standby<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
          How It Works (High-Level Flow)<\/h3>\n\n\n\n
          Step<\/th>Action<\/th><\/tr><\/thead>
          1\ufe0f\u20e3<\/td>Define an external table and enable INMEMORY<\/code><\/td><\/tr>
          2\ufe0f\u20e3<\/td>External table is loaded into IM column store<\/strong> in parallel<\/td><\/tr>
          3\ufe0f\u20e3<\/td>Queries on standby use this in-memory external data<\/strong>, accelerating performance<\/td><\/tr>
          4\ufe0f\u20e3<\/td>You can manage memory use with NO INMEMORY<\/code> or similar directives<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
          \u2705 Example Syntax (Simplified)<\/h2>\n\n\n\n
          CREATE TABLE ext_sales (\n  sale_id    NUMBER,\n  sale_date  DATE,\n  amount     NUMBER\n)\nORGANIZATION EXTERNAL\n(\n  TYPE ORACLE_LOADER\n  DEFAULT DIRECTORY ext_data_dir\n  ACCESS PARAMETERS (\n    RECORDS DELIMITED BY NEWLINE\n    FIELDS TERMINATED BY ','\n    MISSING FIELD VALUES ARE NULL\n    (\n      sale_id, sale_date DATE \"YYYY-MM-DD\", amount\n    )\n  )\n  LOCATION ('sales_data.csv')\n)\nINMEMORY;<\/code><\/code><\/pre>\n\n\n\n
          This will load sales_data.csv<\/code> into IM column store<\/strong>, and the same table can be queried on the standby database<\/strong> with excellent performance.<\/p>\n\n\n\n
          Important Limitations<\/h2>\n\n\n\n
          Limitation<\/th>Description<\/th><\/tr><\/thead>
          \u274c FOR SERVICE<\/code> clause not supported<\/td>You cannot use FOR SERVICE<\/code> with INMEMORY ... DISTRIBUTE<\/code> in primary or standby<\/td><\/tr>
          \ud83d\udd01 Segment control<\/td>Using NO INMEMORY<\/code> will unload<\/strong> the IM external table segment from memory<\/td><\/tr>
          \ud83d\uddc3\ufe0f External table limitations still apply<\/td>Read-only, limited DML, metadata must be accessible to standby if needed<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
          Summary Table<\/h2>\n\n\n\n
          Feature<\/th>Supported on Standby?<\/th>Notes<\/th><\/tr><\/thead>
          In-Memory External Tables<\/td>\u2705 Yes<\/td>Loaded and queried in parallel<\/td><\/tr>
          Parallel Query<\/td>\u2705 Yes<\/td>Fully supported<\/td><\/tr>
          INMEMORY clause<\/td>\u2705 Yes<\/td>Supported with normal usage<\/td><\/tr>
          NO INMEMORY clause<\/td>\u2705 Yes<\/td>Unloads segment from memory<\/td><\/tr>
          FOR SERVICE clause<\/td>\u274c No<\/td>Not supported on either primary or standby<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
          Best Practices<\/h2>\n\n\n\n
          Task<\/th>Recommendation<\/th><\/tr><\/thead>
          Use IM external tables for reporting<\/td>\u2705 Offload heavy file-based analytics to standby<\/td><\/tr>
          Manage memory with NO INMEMORY when needed<\/td>\u2705 Helps control memory usage on standby<\/td><\/tr>
          Avoid FOR SERVICE<\/code> clause<\/td>\u274c Not supported in ADG setup<\/td><\/tr>
          Use parallel queries on standby<\/td>\u2705 Takes full advantage of IM performance<\/td><\/tr>
          Ensure external files are accessible if needed<\/td>\u2705 Especially if standby needs to reference them directly<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
          6. Using Sequences in Oracle Active Data Guard<\/h2>\n\n\n\n
          Oracle Active Data Guard supports global sequences<\/strong> (created with default CACHE<\/code> and NOORDER<\/code>) and session sequences<\/strong>. These sequences can be safely accessed on standby databases with proper caching and setup. This allows read-mostly standby databases to perform limited inserts or operations requiring unique IDs.<\/p>\n\n\n\n
          1\ufe0f\u20e3 Global Sequences on Standby<\/h2>\n\n\n\n
          How They Work<\/h3>\n\n\n\n
            \n
          • When a standby database<\/strong> accesses a global sequence<\/strong> for the first time, it requests a range<\/strong> of sequence numbers from the primary<\/strong>.<\/li>\n\n\n\n
          • The primary database<\/strong> allocates a non-overlapping range based on the CACHE size<\/strong>, and updates the dictionary.<\/li>\n\n\n\n
          • Standby consumes the assigned range. Once exhausted, it requests a new one.<\/li>\n\n\n\n
          • Ensures unique values across all standbys and the primary<\/strong>.<\/li>\n<\/ul>\n\n\n\n
            \n
            \ud83d\udca1 Supported only for sequences with CACHE<\/code> and NOORDER<\/code>.<\/strong><\/p>\n<\/blockquote>\n\n\n\n
            Best Practices<\/h3>\n\n\n\n
              \n
            • \u2757 Always specify CACHE<\/code> with a high enough value<\/strong> to minimize frequent round-trips to the primary.<\/li>\n\n\n\n
            • \u2757 ORDER<\/code> or NOCACHE<\/code> sequences are not supported<\/strong> on standby.<\/li>\n\n\n\n
            • \u2705 Define LOG_ARCHIVE_DEST_n<\/code> on terminal standby pointing back to the primary (needed for redo transport for metadata changes).<\/li>\n<\/ul>\n\n\n\n
              Example: Multi-Standby Environment<\/h3>\n\n\n\n
              Step 1: On Primary<\/h4>\n\n\n\n
              CREATE GLOBAL TEMPORARY TABLE gtt (a INT);\n\nCREATE SEQUENCE g CACHE 10;<\/code><\/code><\/pre>\n\n\n\n
              Step 2: On Standby 1<\/h4>\n\n\n\n
              INSERT INTO gtt VALUES (g.NEXTVAL);\n-- 1\n\nINSERT INTO gtt VALUES (g.NEXTVAL);\n-- 2\n\nSELECT * FROM gtt;\n-- A = 1, 2 (standby 1 gets sequence 1\u201310)<\/code><\/code><\/pre>\n\n\n\n
              Step 3: On Primary<\/h4>\n\n\n\n
              SELECT g.NEXTVAL FROM dual;\n-- 11\nSELECT g.NEXTVAL FROM dual;\n-- 12 (primary gets 11\u201320)<\/code><\/code><\/pre>\n\n\n\n
              Step 4: On Standby 2<\/h4>\n\n\n\n
              INSERT INTO gtt VALUES (g.NEXTVAL);\n-- 21\nINSERT INTO gtt VALUES (g.NEXTVAL);\n-- 22\n\nSELECT * FROM gtt;\n-- A = 21, 22 (standby 2 gets 21\u201330)<\/code><\/code><\/pre>\n\n\n\n
              2\ufe0f\u20e3 Session Sequences on Standby<\/h2>\n\n\n\n
              What Are Session Sequences?<\/h3>\n\n\n\n
                \n
              • Special type of sequence: values are unique only within a session<\/strong>, not across sessions.<\/li>\n\n\n\n
              • Not persistent across sessions.<\/li>\n\n\n\n
              • Created on primary<\/strong> but can be accessed from read-only<\/strong> or read\/write<\/strong> databases (including standby).<\/li>\n\n\n\n
              • Useful with global temporary tables<\/strong> having session-level visibility.<\/li>\n\n\n\n
              • Ignores CACHE<\/code>\/NOCACHE<\/code> and ORDER<\/code>\/NOORDER<\/code>.<\/li>\n<\/ul>\n\n\n\n
                Creating & Altering Session Sequences<\/h3>\n\n\n\n
                \u2705 Create a session sequence:<\/h4>\n\n\n\n
                CREATE SEQUENCE s SESSION;<\/code><\/code><\/pre>\n\n\n\n
                Convert global to session:<\/h4>\n\n\n\n
                ALTER SEQUENCE s SESSION;<\/code><\/code><\/pre>\n\n\n\n
                Convert session to global:<\/h4>\n\n\n\n
                ALTER SEQUENCE s GLOBAL;<\/code><\/code><\/pre>\n\n\n\n
                Example: Using Session Sequences<\/h3>\n\n\n\n
                On Primary<\/h4>\n\n\n\n
                CREATE GLOBAL TEMPORARY TABLE gtt (a INT);\n\nCREATE SEQUENCE s SESSION;<\/code><\/code><\/pre>\n\n\n\n
                On Standby – Session 1<\/h4>\n\n\n\n
                INSERT INTO gtt VALUES (s.NEXTVAL);\n-- 1\nINSERT INTO gtt VALUES (s.NEXTVAL);\n-- 2\n\nSELECT * FROM gtt;\n-- A = 1, 2<\/code><\/code><\/pre>\n\n\n\n
                On Standby – Session 2<\/h4>\n\n\n\n
                INSERT INTO gtt VALUES (s.NEXTVAL);\n-- 1\nINSERT INTO gtt VALUES (s.NEXTVAL);\n-- 2\n\nSELECT * FROM gtt;\n-- A = 1, 2 (values are local to this session)<\/code><\/code><\/pre>\n\n\n\n
                \n
                Result: Each session gets its own private range<\/strong> starting from 1.<\/p>\n<\/blockquote>\n\n\n\n
                Notes & Restrictions<\/h2>\n\n\n\n
                Aspect<\/th>Global Sequence<\/th>Session Sequence<\/th><\/tr><\/thead>
                Accessible on standby<\/td>\u2705 Yes<\/td>\u2705 Yes<\/td><\/tr>
                Unique across system<\/td>\u2705 Yes<\/td>\u274c Only within session<\/td><\/tr>
                Persistence<\/td>\u2705 Yes<\/td>\u274c Session only<\/td><\/tr>
                Supports CACHE\/ORDER<\/td>\u2705 Yes<\/td>\u274c Ignored<\/td><\/tr>
                Defined on primary<\/td>\u2705 Yes<\/td>\u2705 Yes<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
                Summary<\/h2>\n\n\n\n
                  \n
                • Use global sequences<\/strong> with CACHE<\/code> (not NOCACHE<\/code>) for consistent values across all databases.<\/li>\n\n\n\n
                • Use session sequences<\/strong> for lightweight, session-specific ID generation with temp tables.<\/li>\n\n\n\n
                • Be aware of round-trips<\/strong> from standby to primary when cache is exhausted.<\/li>\n\n\n\n
                • Monitor cache size and redo transport when using sequences on standby.<\/li>\n<\/ul>\n\n\n\n
                  7. Using the Result Cache on Physical Standby Databases<\/h2>\n\n\n\n
                  In an Active Data Guard<\/strong> environment, query result caching<\/strong> can be enabled on physical standby databases<\/strong> to improve performance for repeated queries. This reduces computation time for queries that repeatedly access the same data, without impacting the performance of the standby.<\/p>\n\n\n\n
                  Default Behavior<\/h2>\n\n\n\n
                    \n
                  • By default, query results are not cached<\/em><\/strong> on a physical standby database.<\/li>\n\n\n\n
                  • Enabling result caching must be done explicitly for each table<\/strong> involved in recurring queries.<\/li>\n<\/ul>\n\n\n\n
                    How It Works<\/h2>\n\n\n\n
                      \n
                    • Oracle allows the result cache<\/strong> to store query results<\/strong> for enabled tables<\/strong> on physical standby databases.<\/li>\n\n\n\n
                    • A query result will be cached only if all dependent tables<\/strong> used in the query are enabled<\/strong> for result cache using the clause: sqlCopyEditRESULT_CACHE (STANDBY ENABLE)<\/code><\/li>\n<\/ul>\n\n\n\n
                      \n
                      \ud83d\udd38 Views<\/strong> are not cached<\/strong>, even if their underlying tables are enabled.<\/p>\n<\/blockquote>\n\n\n\n
                      \ud83d\udccc When Is Result Cache Used?<\/h2>\n\n\n\n
                      A query will utilize the standby result cache only if:<\/p>\n\n\n\n
                        \n
                      • It\u2019s run on a physical standby<\/strong> in Active Data Guard mode<\/strong>.<\/li>\n\n\n\n
                      • All the tables involved<\/strong> in the query are enabled for result cache.<\/li>\n\n\n\n
                      • The query is repeatable<\/strong> (i.e., returns the same result between redo apply intervals).<\/li>\n<\/ul>\n\n\n\n
                        Enabling Result Cache on Standby Tables<\/h2>\n\n\n\n
                        1. Modify Existing Table<\/h3>\n\n\n\n
                        To enable result cache for an existing table:<\/p>\n\n\n\n
                        ALTER TABLE employee RESULT_CACHE (STANDBY ENABLE);<\/code><\/code><\/pre>\n\n\n\n
                        2. During Table Creation<\/h3>\n\n\n\n
                        To enable result cache while creating the table:<\/p>\n\n\n\n
                        CREATE TABLE employee (\n  emp_id NUMBER,\n  ename VARCHAR2(50),\n  sal   NUMBER\n) RESULT_CACHE (STANDBY ENABLE);<\/code><\/code><\/pre>\n\n\n\n
                        You may also see this written as:<\/p>\n\n\n\n
                        RESULT_CACHE (STABLE ENABLE);<\/code><\/code><\/pre>\n\n\n\n
                        \n
                        STABLE<\/code> tells Oracle the data does not change frequently and is safe to cache.<\/p>\n<\/blockquote>\n\n\n\n
                        \ud83d\udca1 Important Notes<\/h2>\n\n\n\n
                        Feature \/ Behavior<\/th>Details<\/th><\/tr><\/thead>
                        Applies to<\/td>Tables only<\/td><\/tr>
                        Views<\/td>\u274c Not supported (even if base tables are cached)<\/td><\/tr>
                        Multi-table queries<\/td>\u2705 Supported only if all<\/em> involved tables are result-cache enabled<\/td><\/tr>
                        PDB Support<\/td>\u2705 Each PDB in a CDB has its own result cache<\/td><\/tr>
                        Query Hints<\/td>Same syntax and behavior as on the primary<\/td><\/tr>
                        Other RESULT_CACHE<\/code> attributes<\/td>Work the same on standby as on primary<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
                        \ud83e\udde0 Best Practices<\/h2>\n\n\n\n
                          \n
                        • \u2705 Enable result cache for tables used in frequent queries<\/strong> on the standby.<\/li>\n\n\n\n
                        • \u2757 Ensure all tables<\/em> in multi-table queries are enabled<\/strong> for standby cache.<\/li>\n\n\n\n
                        • \u274c Don\u2019t rely on result cache for views<\/strong> or volatile data<\/strong>.<\/li>\n\n\n\n
                        • \ud83d\udd04 Consider query patterns and use hints (e.g., \/*+ RESULT_CACHE *\/<\/code>) if needed.<\/li>\n\n\n\n
                        • \ud83d\udcca Monitor cache performance if using it extensively across multiple PDBs.<\/li>\n<\/ul>\n\n\n\n
                          \u2705 Summary<\/h2>\n\n\n\n
                            \n
                          • Result caching on standby can significantly boost performance<\/strong> for repetitive read queries.<\/li>\n\n\n\n
                          • You must explicitly enable<\/strong> this feature on each table<\/strong> using the STANDBY ENABLE<\/code> clause.<\/li>\n\n\n\n
                          • Only works for tables<\/strong>, not views<\/strong>, and requires Active Data Guard<\/strong>.<\/li>\n\n\n\n
                          • Works per-PDB<\/strong> in container databases.<\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"
                            1. Real-time Query What is Real-time Query? Real-time Query allows you to run read-only queries on a physical standby database while redo apply is running in the background. This means your standby can serve reporting and analytics workloads in real-time, offloading the primary database and maximizing resource usage. \ud83c\udff7\ufe0f This feature is available only with […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"googlesitekit_rrm_CAowu461DA:productID":"","footnotes":""},"categories":[988,1225],"tags":[],"class_list":["post-4219","post","type-post","status-publish","format-standard","hentry","category-data-guard","category-database"],"_links":{"self":[{"href":"https:\/\/w3buddy.com\/blog\/wp-json\/wp\/v2\/posts\/4219","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/w3buddy.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/w3buddy.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/w3buddy.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/w3buddy.com\/blog\/wp-json\/wp\/v2\/comments?post=4219"}],"version-history":[{"count":3,"href":"https:\/\/w3buddy.com\/blog\/wp-json\/wp\/v2\/posts\/4219\/revisions"}],"predecessor-version":[{"id":4223,"href":"https:\/\/w3buddy.com\/blog\/wp-json\/wp\/v2\/posts\/4219\/revisions\/4223"}],"wp:attachment":[{"href":"https:\/\/w3buddy.com\/blog\/wp-json\/wp\/v2\/media?parent=4219"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/w3buddy.com\/blog\/wp-json\/wp\/v2\/categories?post=4219"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/w3buddy.com\/blog\/wp-json\/wp\/v2\/tags?post=4219"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}