ALTER INDEX [schema.]index_name REBUILD 
  PARAMETERS(
      ['UPDATE VECTOR INDEX']
      ['REPLACE vectorizer vectorizer_pref_name']
      )
  [PARALLEL n];

[schema.]index_name

Specifies name of the hybrid vector index that you want to modify.

PARAMETERS(UPDATE VECTOR INDEX)

Recreates only the vector index part of a hybrid vector index with the original preference settings.

PARAMETERS(REPLACE vectorizer vectorizer_pref_name)

Recreates only the vector index part of a hybrid vector index with the specified vectorizer preference settings.

Note:

For non HVI index, replace operation would throw an error, as it cannot replace something that was not present.

PARALLEL

Specifies parallel indexing, as described for the CREATE HYBRID VECTOR INDEX statement.

For detailed information on the PARALLEL clause, see CREATE HYBRID VECTOR INDEX.

• To rebuild all parts of a hybrid vector index:

  Use the following syntax to rebuild all parts of a hybrid vector index (both Oracle Text index and vector index) with the original preference settings:

  Syntax:

  ALTER INDEX index_name REBUILD [PARALLEL n];

  Note that you do not need to specify any PARAMETERS clause when rebuilding both parts of a hybrid vector index.

  Example:

  ALTER INDEX my_hybrid_idx REBUILD;
  
  SELECT (select id from doc_table where rowid = jt.doc_rowid) as doc,
         jt.chunk
  FROM JSON_TABLE(
           DBMS_HYBRID_VECTOR.SEARCH(
             json(
               '{ "hybrid_index_name" : "my_hybrid_idx",
                  "vector" : 
                   { "search_text"    : "vector based search capabilities",
                     "search_mode"    : "CHUNK"
                   },
                  "return" : 
                   { "topN"           : 10 }
               }')
             ),
             '$[*]' COLUMNS doc_rowid  PATH '$.rowid',
                            chunk      PATH '$.chunk_text') jt;

• To rebuild only the vector index part:

  Use the following syntax to rebuild only the vector index part of a hybrid vector index with the original preference settings:

  Syntax:

  ALTER INDEX index_name REBUILD 
    PARAMETERS('UPDATE VECTOR INDEX') [PARALLEL n];

  Example:

  ALTER INDEX my_hybrid_idx REBUILD 
    PARAMETERS('UPDATE VECTOR INDEX') PARALLEL 3;
  
  SELECT (select id from doc_table where rowid = jt.doc_rowid) as doc,
         jt.chunk
  FROM JSON_TABLE(
           DBMS_HYBRID_VECTOR.SEARCH(
             json(
               '{ "hybrid_index_name" : "my_hybrid_idx",
                  "vector" : 
                   { "search_text"    : "vector based search capabilities",
                     "search_mode"    : "CHUNK"
                   },
                  "return" : 
                   { "topN"           : 10 }
               }')
             ),
             '$[*]' COLUMNS doc_rowid  PATH '$.rowid',
                            chunk      PATH '$.chunk_text') jt;

• To recreate indexes with a vectorizer preference:

  You can create a vectorizer preference using the DBMS_VECTOR_CHAIN.CREATE_PREFERENCE PL/SQL function. For detailed information on how to create a vectorizer preference, see CREATE_PREFERENCE. After creating the preference, use the REPLACE vectorizer parameter to pass the preference name here.

  Syntax:

  ALTER INDEX index_name REBUILD 
    parameters('REPLACE vectorizer vectorizer_pref_name') [PARALLEL n];

  Note:

  For non-HVI index, the REPLACE operation would throw an error.

  Example:

  ALTER INDEX my_hybrid_idx REBUILD 
    parameters('REPLACE vectorizer my_vectorizer_pref') [PARALLEL n];

• To replace only the model and/or vector index type

  For an existing HVI index, you can replace the model and/or the index type without specifying the full vectorizer preference using the following syntax.

  Syntax:

  ALTER INDEX schema.index_name REBUILD[
  parameters('REPLACE MODEL model_name VECTOR_IDXTYPE hnsw/ivf')];

  Example:

  ALTER INDEX schema.my_hybrid_idx REBUILD[
  parameters('REPLACE MODEL my_model_name VECTOR_IDXTYPE ivf')];

  Note:

  For non HVI indexes, this syntax would throw an error. If a vectorizer is also specified alongside the model and/or vector_idxtype, it would lead to an error, as only one of either vectorizer or model/vector_idxtype is allowed.

• Converting an existing Text SEARCH or JSON SEARCH index to an HVI

  You can convert (up-convert) an existing Text SEARCH or JSON SEARCH index to an HVI without a full rebuild of the textual/JSON parts of the index using the following syntax. This syntax is supported only for non-HVI index. After this operation, the index would be modified to become an HVI index. This would mean that all HVI operation would be supported and ctx_report would reflect this update correctly.

  Syntax:

  ALTER INDEX schema.index_name REBUILD
  [parameters('add vectorizer_fast vectorizer_pref_name')]; 

  Example:

  ALTER INDEX schema.my_hybrid_idx REBUILD
  [parameters('add vectorizer_fast my_vectorizer_pref')];

  For other cases that are inapplicable to "up-convert", you can convert an existing Text SEARCH or JSON SEARCH index to an HVI with a full rebuild using the following syntax :

  ALTER INDEX schema.index_name REBUILD
  [parameters('add vectorizer vectorizer_pref_name')]; 

  Example:

  ALTER INDEX schema.my_hybrid_idx REBUILD
  [parameters('add vectorizer my_vectorizer_pref)'];