Postgres-Tuned should tune alignment padding

[meglio]

To make the tuned version of the postgres benchmark really tuned, you should optimize the columns layout, see "Column Tetris" at https://stackoverflow.com/a/7431468

[rschu1ze]

Interesting, thanks for the link. Sounds similar to struct padding in C++.

I guess none of us are Postgres experts but if you (or someone else) like to send a PR with a tuned column order, it would be highly welcome (I could do the runtime measurements on a benchmark machine).

[alexey-milovidov]

Could you please edit the script? Then we will re-run it.

[meglio]

Here's the CREATE statement with the improved order of columns:

CREATE TABLE hits
(
    WatchID BIGINT NOT NULL,
    UserID BIGINT NOT NULL,
    FUniqID BIGINT NOT NULL,
    ParamPrice BIGINT NOT NULL,
    RefererHash BIGINT NOT NULL,
    URLHash BIGINT NOT NULL,
    EventTime TIMESTAMP NOT NULL,
    ClientEventTime TIMESTAMP NOT NULL,
    LocalEventTime TIMESTAMP NOT NULL,
    EventDate Date NOT NULL,
    CounterID INTEGER NOT NULL,
    ClientIP INTEGER NOT NULL,
    RegionID INTEGER NOT NULL,
    RefererRegionID INTEGER NOT NULL,
    URLRegionID INTEGER NOT NULL,
    IPNetworkID INTEGER NOT NULL,
    SilverlightVersion3 INTEGER NOT NULL,
    CodeVersion INTEGER NOT NULL,
    HID INTEGER NOT NULL,
    RemoteIP INTEGER NOT NULL,
    WindowName INTEGER NOT NULL,
    OpenerName INTEGER NOT NULL,
    SendTiming INTEGER NOT NULL,
    DNSTiming INTEGER NOT NULL,
    ConnectTiming INTEGER NOT NULL,
    ResponseStartTiming INTEGER NOT NULL,
    ResponseEndTiming INTEGER NOT NULL,
    FetchTiming INTEGER NOT NULL,
    CLID INTEGER NOT NULL,
    JavaEnable SMALLINT NOT NULL,
    GoodEvent SMALLINT NOT NULL,
    CounterClass SMALLINT NOT NULL,
    OS SMALLINT NOT NULL,
    UserAgent SMALLINT NOT NULL,
    IsRefresh SMALLINT NOT NULL,
    RefererCategoryID SMALLINT NOT NULL,
    URLCategoryID SMALLINT NOT NULL,
    ResolutionWidth SMALLINT NOT NULL,
    ResolutionHeight SMALLINT NOT NULL,
    ResolutionDepth SMALLINT NOT NULL,
    FlashMajor SMALLINT NOT NULL,
    FlashMinor SMALLINT NOT NULL,
    TraficSourceID SMALLINT NOT NULL,
    SearchEngineID SMALLINT NOT NULL,
    NetMajor SMALLINT NOT NULL,
    NetMinor SMALLINT NOT NULL,
    UserAgentMajor SMALLINT NOT NULL,
    CookieEnable SMALLINT NOT NULL,
    JavascriptEnable SMALLINT NOT NULL,
    IsMobile SMALLINT NOT NULL,
    MobilePhone SMALLINT NOT NULL,
    AdvEngineID SMALLINT NOT NULL,
    IsArtifical SMALLINT NOT NULL,
    WindowClientWidth SMALLINT NOT NULL,
    WindowClientHeight SMALLINT NOT NULL,
    ClientTimeZone SMALLINT NOT NULL,SilverlightVersion1 SMALLINT NOT NULL,
    SilverlightVersion2 SMALLINT NOT NULL,
    SilverlightVersion4 SMALLINT NOT NULL,
    IsLink SMALLINT NOT NULL,
    IsDownload SMALLINT NOT NULL,
    IsNotBounce SMALLINT NOT NULL,
    IsOldCounter SMALLINT NOT NULL,
    IsEvent SMALLINT NOT NULL,
    IsParameter SMALLINT NOT NULL,
    DontCountHits SMALLINT NOT NULL,
    WithHash SMALLINT NOT NULL,
    Age SMALLINT NOT NULL,
    Sex SMALLINT NOT NULL,
    Income SMALLINT NOT NULL,
    Interests SMALLINT NOT NULL,
    Robotness SMALLINT NOT NULL,
    HistoryLength SMALLINT NOT NULL,
    HTTPError SMALLINT NOT NULL,
    SocialSourceNetworkID SMALLINT NOT NULL,
    HasGCLID SMALLINT NOT NULL,
    ParamCurrencyID SMALLINT NOT NULL,
    Title TEXT NOT NULL,
    URL TEXT NOT NULL,
    Referer TEXT NOT NULL,
    FlashMinor2 TEXT NOT NULL,
    BrowserLanguage TEXT NOT NULL,
    BrowserCountry TEXT NOT NULL,
    SocialNetwork TEXT NOT NULL,
    SocialAction TEXT NOT NULL,
    MobilePhoneModel TEXT NOT NULL,
    Params TEXT NOT NULL,
    SearchPhrase TEXT NOT NULL,
    PageCharset TEXT NOT NULL,
    OriginalURL TEXT NOT NULL,
    SocialSourcePage TEXT NOT NULL,
    ParamOrderID TEXT NOT NULL,
    ParamCurrency TEXT NOT NULL,
    OpenstatServiceName TEXT NOT NULL,
    OpenstatCampaignID TEXT NOT NULL,
    OpenstatAdID TEXT NOT NULL,
    OpenstatSourceID TEXT NOT NULL,
    UTMSource TEXT NOT NULL,
    UTMMedium TEXT NOT NULL,
    UTMCampaign TEXT NOT NULL,
    UTMContent TEXT NOT NULL,
    UTMTerm TEXT NOT NULL,
    FromTag TEXT NOT NULL,
    UserAgentMinor VARCHAR(255) NOT NULL,
    HitColor CHAR NOT NULL
);

[rschu1ze]

Got ERROR: cannot perform COPY FREEZE because the table was not created or truncated in the current subtransaction when I inserted the hits table into Postgres. I used the standard Postgres script (here), and not the tuned script.

[meglio]

Okays guys sorry I don't have time to learn all your setup and correct it. I just wanted to point out that your "optimized posrgres" is not optimized.

[somratdutta]

I tried with the above mentioned optimised create.sql but hit the following error.

CONTEXT:  COPY hits, line 1, column funiqid: ""
ERROR:  invalid input syntax for type bigint: ""
CONTEXT:  COPY hits, line 1, column funiqid: ""
ERROR:  invalid input syntax for type bigint: ""
CONTEXT:  COPY hits, line 1, column funiqid: ""
...

I looked into the issue, and it appears that the error arises from a misalignment between the order of columns defined in the table and the order of columns in the input file (hits.tsv). When the positional order doesn’t match, PostgreSQL ends up trying to interpret data meant for one column as another type.

In other words, if the columns in the table definition and the input file aren’t perfectly aligned, the COPY process can misread values, leading to these type mismatches.

Possible solutions are:

• Adjusting the input file so that its column order matches the table definition.
• Modifying the COPY command (or equivalent script) to explicitly specify column mappings, if possible.

Happy to discuss further or help test any changes!

[somratdutta]

I was able to modify the COPY command and make it work, and the difference is significant while INSERTing the data :

Before Padding Alignment

executing with FILE=xaa
executing with FILE=xab
executing with FILE=xac
executing with FILE=xad
executing with FILE=xae
executing with FILE=xaf
executing with FILE=xag
executing with FILE=xah
COPY 12499688
COPY 12499687
COPY 12499687
COPY 12499687
COPY 12499687
COPY 12499687
COPY 12499687
COPY 12499687

real        8m21.641s
user        0m13.737s
sys        1m36.977s

After Padding Alighnment

executing with FILE=xaa
executing with FILE=xab
executing with FILE=xac
executing with FILE=xad
executing with FILE=xae
executing with FILE=xaf
executing with FILE=xag
executing with FILE=xah
COPY 12499688
COPY 12499687
COPY 12499687
COPY 12499687
COPY 12499687
COPY 12499687
COPY 12499687
COPY 12499687

real        6m52.399s
user        0m14.043s
sys        1m41.489s

The percentage improvement from 8m21.641s to 6m52.399s is approximately 17.79%.

[rschu1ze]

Resolved by #310