Re: Estimating a PK index rebuild with REVERSE

From: Jonathan Lewis <jonathan_at_jlcomp.demon.co.uk>
Date: Wed, 25 Oct 2017 20:33:00 +0000
Message-ID: <LOXP123MB0086E9FD2E38C14F7B3C8A7EA5440_at_LOXP123MB0086.GBRP123.PROD.OUTLOOK.COM>

For reference - you had a fast full scan, so you needed the hint no_index_ffs() as well. (no_)index() is about index range scans and index full scans.

Regards
Jonathan Lewis

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From: oracle-l-bounce_at_freelists.org <oracle-l-bounce_at_freelists.org> on behalf of Luis Santos <lsantos_at_pobox.com> Sent: 25 October 2017 20:53:14
To: Mark W. Farnham
Cc: ORACLE-L
Subject: Re: Estimating a PK index rebuild with REVERSE

Ok, it's here. First our DB version and PSU.

[11g]> _at_psu

COMMENTS                                           VERSION
-------------------------------------------------- ------------------------------
PSU 11.2.0.4.170814                                11.2.0.4

Note that I tried to use hints on CREATE INDEX command. Look the article: https://blog.pythian.com/oracles-create-index-command-can-take-hint

But they did not work.

​​
[11g]> explain plan for
  2 CREATE /*+ NO_INDEX(L PK_TABLE_NAME1) FULL(L) */ UNIQUE INDEX "OWNER_O"."PK_TABLE_NAME1" ON "OWNER_O"."TABLE_NAME1" L ("ID_TABLE_NAME1", "DATA") REVERSE   3 PCTFREE 10 INITRANS 2 MAXTRANS 255   4 STORAGE(
  5 BUFFER_POOL DEFAULT FLASH_CACHE DEFAULT CELL_FLASH_CACHE DEFAULT)   6 TABLESPACE "CRIVO_INDEX" LOCAL
  7 parallel 64
  8 /
Explicado.
U71013576_at_P01CRV.brux0387 [11g]> @xplan PLAN_TABLE_OUTPUT

---

Plan hash value: 961639110

---

| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time | Pstart| Pstop | TQ |IN-OUT| PQ Distrib |

---

| 0 | CREATE INDEX STATEMENT | | 7462M| 111G| 292K (1)| 00:58:27 | | | | | |
| 1 | PX COORDINATOR | | | | | | | | | | |
| 2 | PX SEND QC (RANDOM) | :TQ10000 | 7462M| 111G| | | | | Q1,00 | P->S | QC (RAND) |
| 3 | PX PARTITION RANGE ALL | | 7462M| 111G| | | 1 | 28 | Q1,00 | PCWC | |
| 4 | INDEX BUILD UNIQUE (LOCAL)| PK_TABLE_NAME1 | | | | | 1 | 28 | Q1,00 | PCWP | |
| 5 | SORT CREATE INDEX | | 7462M| 111G| | | | | Q1,00 | PCWP | |
| 6 | INDEX FAST FULL SCAN | PK_TABLE_NAME1 | 7462M| 111G| 124K (1)| 00:24:58 | 1 | 28 | Q1,00 | PCWP | |

---

Query Block Name / Object Alias (identified by operation id):

---

   1 - CRI$1
   6 - CRI$1 / L_at_CRI$1
Column Projection Information (identified by operation id):

---

   1 - SYSDEF[272], SYSDEF[4]
   2 - (#keys=0) SYSDEF[272], SYSDEF[4]
   3 - SYSDEF[272], SYSDEF[4]
   4 - SYSDEF[272]
   5 - (#keys=2) REVERSE("ID_TABLE_NAME1")[22], REVERSE("DATA")[7], "L".ROWID[ROWID,10]
   6 - "L".ROWID[ROWID,10], "ID_TABLE_NAME1"[NUMBER,22], "DATA"[DATE,7]

Note

---

• estimated index size: 225G bytes

--
Att
Luis Santos

[https://lh3.googleusercontent.com/-AD-URpt0jeE/AAAAAAAAAAI/AAAAAAAB-9c/LrffscVVpf8/s90-c-k/photo.jpg]

2017-10-25 12:32 GMT-02:00 Mark W. Farnham <mwf_at_rsiz.com<mailto:mwf_at_rsiz.com>>: Would you add the actual SQL text you submitted?

mwf

From: oracle-l-bounce_at_freelists.org<mailto:oracle-l-bounce_at_freelists.org> [mailto:oracle-l-bounce_at_freelists.org<mailto:oracle-l-bounce_at_freelists.org>] On Behalf Of Luis Santos Sent: Wednesday, October 25, 2017 10:10 AM To: ORACLE-L
Subject: Estimating a PK index rebuild with REVERSE

Hi Oracle-L,

I'm trying to estimate the time necessary to recreate a PK index with the reverse clause. Usually I use explain plan to estimate time and size for a new index.

I did a reverse script from the actual PK index using and DBMS_METADATA and issued the explain plan, adding the reverse clause.

It worked nicely, and the output was.

[11g]> _at_xplan
PLAN_TABLE_OUTPUT

---

Plan hash value: 961639110

---

| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time | Pstart| Pstop | TQ |IN-OUT| PQ Distrib |

---

| 0 | CREATE INDEX STATEMENT | | 7462M| 111G| 292K (1)| 00:58:27 | | | | | |
| 1 | PX COORDINATOR | | | | | | | | | | |
| 2 | PX SEND QC (RANDOM) | :TQ10000 | 7462M| 111G| | | | | Q1,00 | P->S | QC (RAND) |
| 3 | PX PARTITION RANGE ALL | | 7462M| 111G| | | 1 | 28 | Q1,00 | PCWC | |
| 4 | INDEX BUILD UNIQUE (LOCAL)| PK_TABLE_DATA1 | | | | | 1 | 28 | Q1,00 | PCWP | |
| 5 | SORT CREATE INDEX | | 7462M| 111G| | | | | Q1,00 | PCWP | |
| 6 | INDEX FAST FULL SCAN | PK_TABLE_DATA1 | 7462M| 111G| 124K (1)| 00:24:58 | 1 | 28 | Q1,00 | PCWP | |

---

Query Block Name / Object Alias (identified by operation id):

---

   1 - CRI$1
   6 - CRI$1 / TABLE_DATA1_at_CRI$1
Column Projection Information (identified by operation id):

---

   1 - SYSDEF[272], SYSDEF[4]
   2 - (#keys=0) SYSDEF[272], SYSDEF[4]
   3 - SYSDEF[272], SYSDEF[4]
   4 - SYSDEF[272]
   5 - (#keys=2) REVERSE("ID_TABLE_DATA1")[22], REVERSE("DATA")[7], "TABLE_DATA1".ROWID[ROWID,10]
   6 - "TABLE_DATA1".ROWID[ROWID,10], "ID_TABLE_DATA1"[NUMBER,22], "DATA"[DATE,7]

Note

---

• estimated index size: 225G bytes

But this is the evaluation phase. The PK was not, of course, already dropped. So the actual non reverse PK index is been used in the create index plan...

How can I disable the access to the actual PK for this explain plan?

Best regards,
Luis Santos
[https://lh3.googleusercontent.com/-AD-URpt0jeE/AAAAAAAAAAI/AAAAAAAB-9c/LrffscVVpf8/s90-c-k/photo.jpg]

†Ûiÿü0ÁúÞzX¬¶Ê+ƒün– {ú+iÉ^ Received on Wed Oct 25 2017 - 22:33:00 CEST