<PAGE>   1


                                                                   EXHIBIT 10.16

                            SECURED PROMISSORY NOTE



$2,600,000.00                                                      April 6, 2000
                                                           Palo Alto, California


        This Secured Promissory Note is made between the undersigned Clive
Harrison ("Maker") at his address 51 La Honda Ct., Clayton, CA 94517 and
Informatica Corporation, a Delaware corporation (the "Company") at its address
3350 West Bayshore Road. Palo Alto, California 94303. Maker, for value received,
promises to pay to the Company the principal sum of $2,600,000.00 with interest
from the date hereof at a rate of 6.27% per annum, compounded semiannually on
the unpaid balance of such principal sum.

        Such principal and interest shall be due and payable within thirty (30)
days upon the earlier of (i) the date of termination for any reason, with or
without cause, of Maker's employment with the Company as a full-time employee
and (ii) June 30, 2000; provided however, that no interest shall be due if
Maker remains continuously employed as a full-time employee of the Company from
the date hereof through June 30, 2000.

        Interest shall be computed on the basis of a year of 360 days. All
amounts payable under this Note are payable in lawful money of the United
States, without notice, demand, offset or deduction. For purposes of interest
accrual, checks will constitute payment upon receipt.

        This is the Secured Promissory Note referred to in the Security
Agreement of even date herewith between Maker and the Company, and the Company
is entitled to all the benefits provided therein.

        Should the undersigned fail to make full payment of any installment of
principal or interest for a period of 10 days or more after the due date
thereof, the whole unpaid balance on this Note of principal and interest shall
become immediately due at the option of the holder of this Note. Payments of
principal and interest shall be made in lawful money of the United States of
America.

        Maker promises to pay on demand all reasonable out-of-pocket costs of
and expenses of the Company in connection with the collection of amounts due
hereunder, including, without limitation, attorneys' fees incurred in connection
therewith, whether or not any lawsuit is ever filed with respect thereto.

        Maker and any endorsers or guarantors of this Note for themselves, their
heirs, legal representatives, successors and assigns, respectively, severally
waive diligence, presentment, protest and demand and also notice of protest,
demand, dishonor and nonpayment of this Note.


                                       1
<PAGE>   2

        This Note shall inure to the benefit of the Company and its successors
and assigns. The obligations of Maker hereunder shall not be assignable without
the consent of the Company.

        This Note shall be governed by and construed in accordance with the laws
of the State of California. If there is a lawsuit on this Note, the parties
agree to submit to the jurisdiction of the courts of Santa Clara County,
California.



        IN WITNESS WHEREOF, the undersigned has executed and delivered this Note
as of the date first above written.



                                            MAKER




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











                                       2