[ 
https://issues.apache.org/jira/browse/IMPALA-13667?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
 ]

woosuk.ro updated IMPALA-13667:
-------------------------------
    Description: 
h3. *Description*

When using Impala with Ranger for data masking, applying a {{mask_hash}} policy 
to columns in both tables and views results in the {{mask_hash}} function being 
nested multiple times. This behavior leads to redundant hashing operations. Is 
this intended behavior?
h3. *Steps to Reproduce*
 # *Apply Masking Policies:*

 * 
 ** Apply a {{mask_hash}} policy to a specific column (e.g., 
{{{}account_number{}}}) across all tables in two databases, {{temp_db}} and 
{{{}private_db{}}}.

 # *Create a Base Table:*

{code:java}
CREATE TABLE private_db.base_table (
    account_number STRING,
    other_column STRING
);{code}
 # *Create a View Referencing the Base Table:*

{code:java}
CREATE VIEW private_db.base_view AS
SELECT * FROM private_db.base_table;{code}
 
 # *Create Another View Referencing the First View:*

{code:java}
CREATE VIEW temp_db.secondary_view AS
SELECT * FROM private_db.base_view;{code}
 
 # *Execute a Query on the Second View:*

{code:java}
SELECT * FROM temp_db.secondary_view;{code}
h3. *Expected Behavior*

The {{mask_hash}} function should be applied *once* to the {{account_number}} 
column, regardless of the number of view layers referencing the masked table or 
view.
----
h3. *Actual Behavior*

The {{mask_hash}} function is applied *three times* to the {{account_number}} 
column due to nested view references. This results in multiple layers of 
hashing, as observed in both the query execution plan and Ranger audit logs.

*Example Query Execution Plan:*
{code:java}
WARNING: The following tables are missing relevant table and/or column 
statistics.
private_db.base_table
Analyzed query: SELECT * FROM (SELECT mask_hash(account_number) account_number, 
my_account_number FROM
temp_db.secondary_view)F01:PLAN FRAGMENT [UNPARTITIONED] hosts=1 instances=1

 Per-Host Resources: mem-estimate=4.02MB mem-reservation=4.00MB 
thread-reservation=1
PLAN-ROOT SINK    output exprs: 
*mask_hash(mask_hash(mask_hash(account_number)))*, my_account_number    
mem-estimate=4.00MB mem-reservation=4.00MB spill-buffer=2.00MB 
thread-reservation=0   {code}
*Ranger Audit Logs:*
 # *temp_db.secondary_view account_number column masking*
{code:java}
{
    "access": "mask_hash",
    "resource": "temp_db/secondary_view/account_number",
    "resType": "@column",
    "reqData": "SELECT * FROM temp_db.secondary_view"
}{code}

 # *private_db.base_view account_number column masking*
{code:java}
{
    "access": "mask_hash",
    "resource": "private_db/base_view/account_number",
    "resType": "@column",
    "reqData": "SELECT * FROM temp_db.secondary_view"
}{code}

 # *private_db.base_table account_number column masking*

{code:java}
{     
    "access": "mask_hash",     
    "resource": "private_db/base_table/account_number",     
    "resType": "@column",     
    "reqData": "SELECT * FROM temp_db.secondary_view" 
}{code}

*Environment*
 - Impala: 4.4.0
 - Ranger: 2.3.0
 
 

  was:
h3. *Description*

When using Impala with Ranger for data masking, applying a {{mask_hash}} policy 
to columns in both tables and views results in the {{mask_hash}} function being 
nested multiple times. This behavior leads to redundant hashing operations. Is 
this intended behavior?
h3. *Steps to Reproduce*
 # *Apply Masking Policies:*

 * 
 ** Apply a {{mask_hash}} policy to a specific column (e.g., 
{{{}account_number{}}}) across all tables in two databases, {{temp_db}} and 
{{{}private_db{}}}.

 # *Create a Base Table:*

{code:java}
CREATE TABLE private_db.base_table (
    account_number STRING,
    other_column STRING
);{code}
 # *Create a View Referencing the Base Table:*

{code:java}
CREATE VIEW private_db.base_view AS
SELECT * FROM private_db.base_table;{code}
 
 # *Create Another View Referencing the First View:*

{code:java}
CREATE VIEW temp_db.secondary_view AS
SELECT * FROM private_db.base_view;{code}
 
 # *Execute a Query on the Second View:*

{code:java}
SELECT * FROM temp_db.secondary_view;{code}
h3. *Expected Behavior*

The {{mask_hash}} function should be applied *once* to the {{account_number}} 
column, regardless of the number of view layers referencing the masked table or 
view.
----
h3. *Actual Behavior*

The {{mask_hash}} function is applied *three times* to the {{account_number}} 
column due to nested view references. This results in multiple layers of 
hashing, as observed in both the query execution plan and Ranger audit logs.

*Example Query Execution Plan:*
{code:java}
WARNING: The following tables are missing relevant table and/or column 
statistics.
private_db.base_table
Analyzed query: SELECT * FROM (SELECT mask_hash(account_number) account_number, 
my_account_number FROM
temp_db.secondary_view)F01:PLAN FRAGMENT [UNPARTITIONED] hosts=1 instances=1

 Per-Host Resources: mem-estimate=4.02MB mem-reservation=4.00MB 
thread-reservation=1
PLAN-ROOT SINK    output exprs: 
*mask_hash(mask_hash(mask_hash(account_number)))*, my_account_number    
mem-estimate=4.00MB mem-reservation=4.00MB spill-buffer=2.00MB 
thread-reservation=0   {code}
*Ranger Audit Logs:*
 # *temp_db.secondary_view account_number column masking*
{code:java}
{
    "access": "mask_hash",
    "resource": "temp_db/secondary_view/account_number",
    "resType": "@column",
    "reqData": "SELECT * FROM temp_db.secondary_view"
}{code}
 

 # *private_db.base_view account_number column masking*
{code:java}
{
    "access": "mask_hash",
    "resource": "private_db/base_view/account_number",
    "resType": "@column",
    "reqData": "SELECT * FROM temp_db.secondary_view"
}{code}

 # *private_db.base_table account_number column masking*

{code:java}
{
    "access": "mask_hash",
    "resource": "private_db/base_table/account_number",
    "resType": "@column",
    "reqData": "SELECT * FROM temp_db.secondary_view"
}{code}
*Environment*
 - Impala: 4.4.0
 - Ranger: 2.3.0
 
 


> Unexpected Nested mask_hash Functions When Using Views in Impala with Ranger
> ----------------------------------------------------------------------------
>
>                 Key: IMPALA-13667
>                 URL: https://issues.apache.org/jira/browse/IMPALA-13667
>             Project: IMPALA
>          Issue Type: Question
>          Components: Frontend
>            Reporter: woosuk.ro
>            Priority: Minor
>
> h3. *Description*
> When using Impala with Ranger for data masking, applying a {{mask_hash}} 
> policy to columns in both tables and views results in the {{mask_hash}} 
> function being nested multiple times. This behavior leads to redundant 
> hashing operations. Is this intended behavior?
> h3. *Steps to Reproduce*
>  # *Apply Masking Policies:*
>  * 
>  ** Apply a {{mask_hash}} policy to a specific column (e.g., 
> {{{}account_number{}}}) across all tables in two databases, {{temp_db}} and 
> {{{}private_db{}}}.
>  # *Create a Base Table:*
> {code:java}
> CREATE TABLE private_db.base_table (
>     account_number STRING,
>     other_column STRING
> );{code}
>  # *Create a View Referencing the Base Table:*
> {code:java}
> CREATE VIEW private_db.base_view AS
> SELECT * FROM private_db.base_table;{code}
>  
>  # *Create Another View Referencing the First View:*
> {code:java}
> CREATE VIEW temp_db.secondary_view AS
> SELECT * FROM private_db.base_view;{code}
>  
>  # *Execute a Query on the Second View:*
> {code:java}
> SELECT * FROM temp_db.secondary_view;{code}
> h3. *Expected Behavior*
> The {{mask_hash}} function should be applied *once* to the {{account_number}} 
> column, regardless of the number of view layers referencing the masked table 
> or view.
> ----
> h3. *Actual Behavior*
> The {{mask_hash}} function is applied *three times* to the {{account_number}} 
> column due to nested view references. This results in multiple layers of 
> hashing, as observed in both the query execution plan and Ranger audit logs.
> *Example Query Execution Plan:*
> {code:java}
> WARNING: The following tables are missing relevant table and/or column 
> statistics.
> private_db.base_table
> Analyzed query: SELECT * FROM (SELECT mask_hash(account_number) 
> account_number, my_account_number FROM
> temp_db.secondary_view)F01:PLAN FRAGMENT [UNPARTITIONED] hosts=1 instances=1
>  Per-Host Resources: mem-estimate=4.02MB mem-reservation=4.00MB 
> thread-reservation=1
> PLAN-ROOT SINK    output exprs: 
> *mask_hash(mask_hash(mask_hash(account_number)))*, my_account_number    
> mem-estimate=4.00MB mem-reservation=4.00MB spill-buffer=2.00MB 
> thread-reservation=0   {code}
> *Ranger Audit Logs:*
>  # *temp_db.secondary_view account_number column masking*
> {code:java}
> {
>     "access": "mask_hash",
>     "resource": "temp_db/secondary_view/account_number",
>     "resType": "@column",
>     "reqData": "SELECT * FROM temp_db.secondary_view"
> }{code}
>  # *private_db.base_view account_number column masking*
> {code:java}
> {
>     "access": "mask_hash",
>     "resource": "private_db/base_view/account_number",
>     "resType": "@column",
>     "reqData": "SELECT * FROM temp_db.secondary_view"
> }{code}
>  # *private_db.base_table account_number column masking*
> {code:java}
> {     
>     "access": "mask_hash",     
>     "resource": "private_db/base_table/account_number",     
>     "resType": "@column",     
>     "reqData": "SELECT * FROM temp_db.secondary_view" 
> }{code}
> *Environment*
>  - Impala: 4.4.0
>  - Ranger: 2.3.0
>  
>  



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