Re: [JDBC] JDBC: Better initial capacity for StringBuffers reduces - Mailing list pgsql-patches

Fernando,

Patch applied to CVS head.

thanks,
--Barry


Fernando Nasser wrote:
> Regardless of the streaming patches that are floating around, we should
> fix the allocation of the StringBuffers.
>
> On the AbstractJdbc1Statement one, the initial space allocated for the
> buffer will never be enough because of the quotes, so we end up using 3
> times the size of the object + 1 and having to copy it from the initial
> buffer to the double size one. Instead of just adding '+2' I gave it
> some slack for the escaping of quotes.
>
> The one in PGbytea may raise some eyebrows, but I can guarantee you that
> it _always_ win, when compared to allocate just the object size for at
> least that amount of space.
>
> The changes above reduce by 33% (in the worst case) the memory
> requirements for uploading data (without the streaming patches).
> Although not that important for smaller data types (once the streaming
> is in place we will not send large ones through this path anymore),
> there is no reason to waste memory so I suggest we check this in.
>
> Regards to all.
>
>
>
> ------------------------------------------------------------------------
>
> Index: src/interfaces/jdbc/org/postgresql/jdbc1/AbstractJdbc1Statement.java
> ===================================================================
> RCS file: /projects/cvsroot/pgsql-server/src/interfaces/jdbc/org/postgresql/jdbc1/AbstractJdbc1Statement.java,v
> retrieving revision 1.21
> diff -c -p -r1.21 AbstractJdbc1Statement.java
> *** src/interfaces/jdbc/org/postgresql/jdbc1/AbstractJdbc1Statement.java    2003/05/03 20:40:45    1.21
> --- src/interfaces/jdbc/org/postgresql/jdbc1/AbstractJdbc1Statement.java    2003/05/14 05:58:21
> *************** public abstract class AbstractJdbc1State
> *** 1020,1026 ****
>               synchronized (sbuf)
>               {
>                   sbuf.setLength(0);
> !                 sbuf.ensureCapacity(x.length());
>                   int i;
>
>                   sbuf.append('\'');
> --- 1020,1026 ----
>               synchronized (sbuf)
>               {
>                   sbuf.setLength(0);
> !                 sbuf.ensureCapacity(x.length() + (int)(x.length() / 10));
>                   int i;
>
>                   sbuf.append('\'');
> Index: src/interfaces/jdbc/org/postgresql/util/PGbytea.java
> ===================================================================
> RCS file: /projects/cvsroot/pgsql-server/src/interfaces/jdbc/org/postgresql/util/PGbytea.java,v
> retrieving revision 1.7
> diff -c -p -r1.7 PGbytea.java
> *** src/interfaces/jdbc/org/postgresql/util/PGbytea.java    2003/03/07 18:39:46    1.7
> --- src/interfaces/jdbc/org/postgresql/util/PGbytea.java    2003/05/14 05:58:22
> *************** public class PGbytea
> *** 68,74 ****
>       {
>           if (p_buf == null)
>               return null;
> !         StringBuffer l_strbuf = new StringBuffer(p_buf.length);
>           for (int i = 0; i < p_buf.length; i++)
>           {
>               int l_int = (int)p_buf[i];
> --- 68,74 ----
>       {
>           if (p_buf == null)
>               return null;
> !         StringBuffer l_strbuf = new StringBuffer(2 * p_buf.length);
>           for (int i = 0; i < p_buf.length; i++)
>           {
>               int l_int = (int)p_buf[i];
>
>
> ------------------------------------------------------------------------
>
>
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