Clone Tools
Constraints
Constraints: committers
 
Constraints: files
Constraints: dates
Turning on CQD TRAF_UPSERT_TO_EFF_TREE 'ON' by default. Fixed a couple of issues during inlining.1. RI constraints had to be handled .2. The Sequence node had to be modified to avoid an unneeded copyTree that was causing problems with subqueries. 3. A new flag introduced to identify that we are int he midst of this transformation. Modified TEST015 to print out the details for the new transformation.

  1. … 8 more files in changeset.
TRAFODION-1586 Add support for external Traf tables mappedd to HBase tables

This is the initial support for HBase mapped tables.

A doc for external manuals will be added later.

regress/seabase/TEST022 contains various testcases.

  1. … 77 more files in changeset.
Added regression test and fixed all the review comments.

  1. … 5 more files in changeset.
Changes to transform an upsert plan into an efficient plan when indexes are present and allow for rowset type operations. The plan makes use of existing operators to eliminate duplicates at the source so we don't need to perform a row at a time check and put operation. The code is currently turned off with a CD traf_upsert_to_eff_tree.

  1. … 8 more files in changeset.
[TRAFODION-2317] Infrastructure for common subexpressions

This is a first set of changes to allow us to make use of CTEs

(Common Table Expressions) declared in WITH clauses and to create

a temp table for them that is then read multiple times in the query.

This also includes a fix for

[TRAFODION-2280] Need to remove salt columns from uniqueness constraints

Summary of changes:

- Adding a unique statement number in CmpContext

- Moving the execHiveSQL method from the OSIM code to CmpContext

- Adding a list of common subexpressions and their references

to CmpStatement

- Adding the ability to the Hive Truncate operator to drop the

table when the TCB gets deallocated

- Adding the ability to the HDFS scan to compute scan ranges at

runtime. Those are usually determined in the compiler. This is

only supported for simple, non-partitioned, delimited tables.

We need this because we populate the temp table and read from

in in the same statement, without the option of compiling

after we inserted into the temp table.

- Special handling in the MapValueIds node of common subexpressions.

See the comment in MapValueId::preCodeGen().

- Moved the binder code to create a FastExtract node into a new

method FastExtract::makeFastExtractTree(), to be able to call

it from another place.

- MapValueIds no longer looks at the "used by MVQR flag" to determine

the method for VEGRewrite. Instead it checks whether a list of

values has been provided to do this.

- Adding a new method, RelExpr::prepareMeForCSESharing, that is

kind of an "unnormalizer", undoing some of the normalizer

transformations.

- Implementing the steps for common subexpression materializations

described below.

- Adding the ability to suppress the Hive timestamp modification

check when truncating a Hive table

- Adding an optimizer rule to eliminate CommonSubExprRef nodes.

These nodes should not normally survive past the SQO phase, but

if the SQO phase gets interrupted by an exception, that could

happen, since we then fall back to a copy of the tree before

SQO. In the future, we can consider cost-based decision on

what to do with common subexpressions.

- Adding CommonSubExprRef nodes in the parser whenever we expand

a CTE reference.

- Adding cleanup code to the "cleanup obsolete volatile tables"

command that removes obsolete Hive tables used for common

subexpressions.

Other changes contained in this change set:

- Optimization for empty scans, like select * from t where 1=0

This now generates a cardinality constraint with 0 rows, which

can be used later to eliminate parts of a tree.

(file OptLogRelExpr.cpp)

- [TRAFODION-2280] Need to remove salt columns from uniqueness

constraints generated on salted tables.

(file OptLogRelExpr.cpp)

- Got rid of the now meaningless "seamonster" display in EXPLAIN.

(file GenExplain.cpp and misc. expected files)

- Suppress display of "zombies" in the cstat command. Otherwise,

these zombies (marked as <defunct>) prevent Trafodion from

starting, because they are incorrectly considered "orphan"

processes. This could require a reboot when no reboot is necessary.

(file core/sqf/sql/scripts/pstat)

Incomplete list of things left to be done:

- TRAFODION-2316: Hive temp tables are not secure. Use volatile

tables instead.

- TRAFODION-2315: Add heuristics to decide when to use the temp table

approach.

- TRAFODION-2320: Make subquery unnesting work with common subexpressions.

Generated Plans

---------------

The resulting query plan for a query Q with n common

subexpressions CSE1 ... CSEn looks like this:

Root

|

MapValueIds

|

BlockedUnion

/ \

Union Q

/ \

... CTn

/

Union

/ \

CT1 CT2

Each of the CTi variables looks like the following, an

INSERT OVERWRITE TABLE tempi ...

BlockedUnion

/ \

Truncate FastExtract TEMPi

TEMPi |

CSEi

The original query Q has the common subexpressions replaced

with the following:

MapValueIds

|

scan TEMPi

Here is a simple query and its explain:

prepare s from

with cse1 as (select d_date_sk, d_date, d_year, d_dow, d_moy from date_dim)

select x.d_year, y.d_date

from cse1 x join cse1 y on x.d_date_sk = y.d_date_sk

where x.d_moy = 3;

>>explain options 'f' s;

LC RC OP OPERATOR OPT DESCRIPTION CARD

---- ---- ---- -------------------- -------- -------------------- ---------

11 . 12 root 1.46E+005

5 10 11 blocked_union 1.46E+005

7 9 10 merge_join 7.30E+004

8 . 9 sort 1.00E+002

. . 8 hive_scan CSE_TEMP_CSE1_MXID11 1.00E+002

6 . 7 sort 5.00E+001

. . 6 hive_scan CSE_TEMP_CSE1_MXID11 5.00E+001

1 4 5 blocked_union 7.30E+004

2 . 4 hive_insert CSE_TEMP_CSE1_MXID11 7.30E+004

. . 2 hive_scan DATE_DIM 7.30E+004

. . 1 hive_truncate 1.00E+000

--- SQL operation complete.

>>

CQDs to control common subexpressions

-------------------------------------

CSE_FOR_WITH is the master switch.

CQD Value Default Behavior

--------------------- --------- ------- ---------------------------------------

CSE_FOR_WITH OFF Y No change

ON Insert a CommonSubExprRef node in the

tree whenever we reference a CTE

(table defined in a WITH clause)

CSE_USE_TEMP OFF Y Disable creation of temp tables

for common subexpressions

SYSTEM Same as OFF for now

ON Always create a temp table for

common subexpressions where possible

CSE_DEBUG_WARNINGS OFF Y No change

ON Emit diagnostic warnings that show why

we didn't create temp tables for

common subexpressions

CSE_CLEANUP_HIVE_TABLES OFF Y No change

ON Cleanup Hive tables used for CSEs with

the "cleanup obsolete volatile tables"

command

CommonSubExprRef relational operators

-------------------------------------

This is a new RelExpr class that is introduced. It marks the common

subexpressions in a RelExpr tree. This operator remembers the name of

a common subexpression (e.g. the name used in the WITH clause).

Multiple such operators can reference to the same name. Each of

these references has a copy of the tree.

Right now, these operators are created in the parser when we expand a

CTE (Common Table Expression), declared in a WITH clause. If the CTE

is referenced only once, then the CommonSubExprRef operator is removed

in the binder - it also doesn't live up to its name in this case.

The remaining CommonSubExprRef operators keep track of various changes

to their child trees, during the binder and normalizer phases. In

particular, it tracks which predicates are pushed down into the child

tree and which outputs are eliminated.

The CmpStatement object keeps a global list of all the

CommonSubExprRef operators in a statement, so the individual operators

have a way to communicate with their siblings:

- A statement can have zero or more named common subexpressions.

- Each reference to a common subexpression is marked in the RelExpr

tree with a CommonSubExprRef node.

- In the binder and normalizer, common subexpressions are expanded,

meaning that multiple copies of them exist, one copy per

CommonSubExprRef.

- Common subexpressions can reference other common subexpressions,

so they, together with the main query, for a DAG (directed

acyclic graph) of dependencies.

- Note that CTEs declared in a WITH clause but not referenced are

ignored and are not part of the query tree.

In the semantic query optimization phase (SQO), the current code makes

a heuristic decision what to do with common subexpressions - to

evaluate them multiple times (expand) or to create a temporary table

once and read that table multiple times.

If we decide to expand, the action is simple: Remove the

CommonSubExprRef operator from the tree and replace it with its child.

If we decide to create a temp table, things become much more difficult.

We need to do several steps:

- Pick one of the child trees of the CommonSubExprRefs as the one to

materialize.

- Undo any normalization steps that aren't compatible with the other

CommonSubExprRefs. That means pulling out predicates that are not

common among the references and adding back outputs that are

required by other references. If that process fails, we fall back

and expand the expressions.

- Create a temp table tmp.

- Prepare an INSERT OVERWRITE TABLE tmp SELECT * FROM cse tree

that materializes the common subexpression in a table.

- Replace the CommonSubExprRef nodes with scans of the temp table.

- Hook up the insert query tree with the main query, such that it

is executed before the main query starts.

Temporary tables

----------------

At this time, temporary tables are created as Hive tables, with a

fabricated, unique name, including the session id, a unique statement

number within the session, and a unique identifier of the common

subexpression within the statement. The temporary table is created at

compile time. The query plan contains an operator to truncate the

table before populating it. The "temporary" Hive table is dropped when

the executor TCB is deallocated.

Several issues are remaining with this approach:

- If the process exits before executing and deallocating the statement,

the Hive table is not cleaned up.

Solution (TBD): Clean up these tables like we clean up left-over

volatile tables. Both are identified by the session id.

- If the executor runs into memory pressure and deallocates the TCB,

then allocates it again at a later time, the temp table is no longer

there.

Solution (TBD): Use AQR to recompile the query and create a new table.

- Query cache: If we cache a query, multiple queries may end up with

the same temporary table. This works ok as long as these queries are

executed serially, but it fails if both queries are executed at the

same time (e.g. open two cursors and fetch from both, alternating).

Solution (TBD): Add a CQD that disables caching queries with temp tables

for common subexpressions.

In the future we also want to support volatile tables. However, those also

have issues:

- Volatile tables aren't cleaned up until the session ends. If we run

many statements with common subexpressions, that is undesirable. So,

we have a similar cleanup problem as with Hive tables.

- Volatile tables take a relatively long time to create.

- Insert and scan rates on volatile Trafodion tables are slower than

those on Hive tables.

To-do items are marked with "Todo: CSE: " in the code.

  1. … 78 more files in changeset.
Create NACollection objects on NAHeap. Avoid use of system heap as far as possible

  1. … 50 more files in changeset.
jira TRAFODION-2184 additional changes

  1. … 4 more files in changeset.
metadata access performance improvement for accessing traf objects

Packed version of descriptor structures is now stored in traf TEXT

table during various DDL operations.

During dml, if packed descriptors exist, then they are read and used.

If they dont exist, then descriptors are generated on the fly.

Descriptor classes are defined in file sqlcat/TrafDDLdesc.h and

are based off the older desc structures from desc.h.

These are simplified and class'ified version of the older structures

and are versioned. Changes to these classes should be done carefully

by either using filler bytes or versioning them.

2 new cqds, traf_store_object_descriptor and traf_read_object_descriptor,

are added to control if packed descs should be stored/read.

These are currently set to OFF by default but are enabled during

regressions run. Once this feature is tested, these cqds will be turned

on by default.

In addition, some helper commands have been added to manipulate descrs.

Syntax:

alter table t [check|generate|delete|disable|enable] stored descritors

If authorization is enabled, then auth/priv specific info

is generated on the fly and currently not stored in metadata.

In a later checkin, these will also be stored in metadata.

  1. … 74 more files in changeset.
JIRA TRAFODION-2072 plus few more

-- long varchars (> 32K) are handled for traf (regular and aligned)

and hive tables

-- showddl for hive tables shows traf and hive definitions

-- traf external tables can optionally take columns attrs that would

overwrite corresponding hive col attrs

-- metadata is updated with info no whether col attrs were specified

-- 'repeat' function can optionally take a max length parameter

-- error is returned if an external table is created for non-hive

-- tests added to regress/seabase/TEST031 and hive/TEST009

  1. … 44 more files in changeset.
[TRAFODION-2021] Internal error on upsert with index

In this particular case, the extra nodes added by index maintenance

and the WHERE clause interacted in a way that caused some missing

characteristic inputs, leading to the generator error. The fix is to

add the required inputs not directly to the nodes, but as "outer

references" to the BindScope, so that they get added automatically to

any nodes created in that BindScope. Since the predicates get created

by a method called at a higher level, I also needed to add a "remote

control" feature for the BindScope of a MergeUpdate node.

Also: [TRAFODION-2026] Upsert fails on table with nullable key column.

When creating the predicate that links the target clustering key with

the corresponding source values, use "special nulls" semantics for

nullable key columns, so a comparesion NULL = NULL is allowed and

yields TRUE.

  1. … 4 more files in changeset.
[TRAFODION-1791] UPSERT with bare one row subquery in VALUES clause fails [TRAFODION-1792] UPSERT with parameters in VALUES clause fails

Please see JIRA for explanation of the fix. Fix for 1791 is in NormRelExpr.cpp.

While change in BindRelExpr.cpp is for 1792. Regression tests have been added with a

few different variations.

  1. … 7 more files in changeset.
jira-1443 final.

  1. … 16 more files in changeset.
JIRA TRAFODION-19 && TRAFODION-1483

JIRA TRAFODION-19:

Made the following changes:

Removed support for locklength from the parser

Test and fix issues with create table variants

Made recommended changes as mentioned in the initial delivery

Rename some of the variable names to make them more informative

Assume prefix length for HIVE and HBASE tables can be different and verify code works correctly

Fix commented code to be correct and remove lines no longer needed

Update error text for messages 1180 to include external table type

Beefed up the new regression test (hive/TEST009)

Check column list from hive descriptor with external table description and return an error if there is a mismatch

Add an error if the user specifies a different target schema name than the source

Allow someone with privileges to drop HIVE exernal schemas

JIRA TRAFODION-1483:

Added support for external HBase tables similar to Hive table support

  1. … 33 more files in changeset.
Part 2 of changes to update license text in Trafodion source

This check-in updates license text in all source files in the

core/sql directory. Remaining directories will be done in

later check-ins.

  1. … 3147 more files in changeset.
Merge remote branch 'core/master'

  1. … 108 more files in changeset.
Merge remote branch 'core/master'

  1. … 2817 more files in changeset.
Move core into subdir to combine repos

  1. … 10768 more files in changeset.
Move core into subdir to combine repos

  1. … 10622 more files in changeset.
Move core into subdir to combine repos

Use: git log --follow -- <file>

to view file history thru renames.

  1. … 10837 more files in changeset.