RE: oracle v SS
Date: Fri, 8 Nov 2019 08:12:12 +0000
Message-ID: <27135_1573200754_5DC52372_27135_15573_1_695c5c84e17c4232b3f812a88bf32c40_at_vontobel.com>
Hi Kellyn,
I embedded my answers below.
The access over a secondary index requires an additional clustered index lookup for getting a row. Consequently, if the clustered index depth is, say, four, this will require four additional logical reads per fetched row. To do justice to SQL Server, the clustered index lookup could be avoided by including all of the selected columns in the secondary index. However, this might become quite a challenging task in a DWH allowing ad-hoc queries. In contrast, Oracle tries to maintain ROWIDs in the secondary index, and therefore, doesn’t require those additional reads. I elaborated on that topic here: https://nenadnoveljic.com/blog/index-organized-table-vs-clustered-index/ .
Unlike Oracle, SQL Server isn’t specifically compiled for Linux. There is a translation layer instead, see https://cloudblogs.microsoft.com/sqlserver/2016/12/16/sql-server-on-linux-how-introduction/ . Consequently, the tools tracing user space calls can’t resolve addresses of SQL Server functions – which renders them unusable. For example, see a (cryptic) pstack output of a SQL Server process, which isn’t helpful at all:
pstack 1095
In contrast, pstack output of an Oracle process provides a genuinely useful information:
pstack 29069
According to https://docs.microsoft.com/en-us/power-bi/report-server/install-report-server , Power BI is available on-premise as well.
Best regards,
Nenad
Thread 2 (Thread 0x7fe874b9f700 (LWP 2557)):
#0 0x00007fe87ef5dcef in ppoll () from /lib64/libc.so.6
#1 0x00005583a0cf7d41 in ?? ()
#2 0x00007fe881b46ea5 in start_thread () from /lib64/libpthread.so.0
#3 0x00007fe87ef688cd in clone () from /lib64/libc.so.6
Thread 1 (Thread 0x7fe881f5e0c0 (LWP 1095)):
#0 0x00007fe881b4e1d9 in waitpid () from /lib64/libpthread.so.0
#1 0x00005583a0cf8373 in ?? ()
#2 0x00005583a0d4c955 in ?? ()
#3 0x00005583a0d4d61f in ?? ()
#4 0x00005583a0d23eb1 in ?? ()
#5 0x00005583a0ce27df in ?? ()
#6 0x00007fe87ee8c545 in __libc_start_main () from /lib64/libc.so.6
#7 0x00005583a0cdfbba in ?? ()
#0 0x00007f627002015a in semtimedop () from /lib64/libc.so.6
#1 0x0000000012840365 in sskgpwwait ()
#2 0x000000001283c4bb in skgpwwait ()
#3 0x0000000012034d9a in ksliwat ()
#4 0x000000001203414c in kslwaitctx ()
#5 0x0000000012657e20 in ksarcv ()
#6 0x0000000003a2837a in ksbabs ()
#7 0x0000000003a46933 in ksbrdp ()
#8 0x0000000003e2a8cd in opirip ()
#9 0x00000000026d3265 in opidrv ()
#10 0x0000000003185685 in sou2o ()
#11 0x0000000000da9f1d in opimai_real ()
#12 0x0000000003191821 in ssthrdmain ()
#13 0x0000000000da9e40 in main ()
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